Changes between Version 1 and Version 2 of TracUpgrade


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Timestamp:
Jun 21, 2020, 8:42:19 PM (2 years ago)
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trac
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  • TracUpgrade

    v1 v2  
    1 = Upgrade Instructions =
     1= Upgrade Instructions
    22[[TracGuideToc]]
    3 
    4 A Trac environment sometimes needs to be upgraded before it can be used with a new version of Trac. This document describes the steps necessary to upgrade an environment.
    5 
    6  '''Note''': ''Environment upgrades are not necessary for minor version releases unless otherwise noted. For example, there's no need to upgrade a Trac environment created with (or upgraded) 0.8.0 when installing 0.8.4 (or any other 0.8.x release).''
    7 
    8 == General Instructions ==
    9 
    10 Typically, there are four steps involved in upgrading to a newer version of Trac:
    11 
    12 === Update the Trac Code ===
    13 
    14 Get the new version of Trac, either by downloading an offical release package or by checking it out from the [http://projects.edgewall.com/trac/wiki/SubversionRepository Subversion repository].
    15 
    16 If you're doing a major version upgrade (such as from 0.8 to 0.9), it is ''highly'' recommended that you first remove the existing Trac code. To do this, you need to delete the `trac` directory from the Python `lib/site-packages` directory. You may also want to remove the Trac `cgi-bin`, `htdocs`, `templates` and `wiki-default` directories that are commonly found in a directory called `share/trac` (the exact location depends on your platform).
    17 
    18 If you have a source distribution, you need to run
    19 {{{
    20 python setup.py install
    21 }}}
    22 
    23 to install the new version. If you've downloaded the Windows installer, you execute it, and so on.
    24 
    25 === Upgrade the Trac Environment ===
    26 
    27 Unless noted otherwise, upgrading between major versions (such as 0.8 and 0.9) involves changes to the database schema, and possibly the layout of the [wiki:TracEnvironment environment directory]. Fortunately, Trac provides automated upgrade scripts to ease the pain. These scripts are run via [wiki:TracAdmin trac-admin]:
    28 {{{
     3[[PageOutline(2-4,,inline,unnumbered)]]
     4
     5== Instructions
     6
     7Typically, there are seven steps involved in upgrading to a newer version of Trac:
     8
     9=== 1. Bring your server off-line
     10
     11It is not a good idea to update a running server: the server processes may have parts of the current packages cached in memory, and updating the code will likely trigger [#ZipImportError internal errors].
     12
     13Although a database backup will be implicitly created by default when upgrading the environment, it is always a good idea to perform a full backup of the environment using the [TracBackup hotcopy] command before beginning.
     14
     15=== 2. Update the Trac Code #UpdatetheTracCode
     16
     17Get the new version as described in TracInstall, or through your operating system package manager.
     18
     19If you already an earlier version of Trac installed via `easy_install`, it might be easiest to also use `easy_install` to upgrade your Trac installation:
     20
     21{{{#!sh
     22easy_install --upgrade Trac==1.2
     23}}}
     24
     25You may also want to remove the pre-existing Trac code by deleting the `trac` directory from the Python `lib/site-packages` directory, or remove Trac `.egg` files from former versions.
     26The location of the site-packages directory depends on the operating system and the location in which Python was installed. However, the following locations are typical:
     27 * on Linux: `/usr/lib/python2.X/site-packages`
     28 * on Windows: `C:\Python2.X\lib\site-packages`
     29 * on MacOSX: `/Library/Python/2.X/site-packages`
     30
     31You may also want to remove the directory in which your static resources are [TracInstall#cgi-bin deployed]. The exact location depends on your platform. This cleanup is not mandatory, but makes it easier to troubleshoot issues later on, as your installation is uncluttered by code or templates from a previous release that is not used anymore. As usual, make a backup before actually removing things.
     32
     33=== 3. Upgrade the Trac Environment #UpgradetheTracEnvironment
     34
     35Environment upgrades are not necessary for minor version releases unless otherwise noted.
     36
     37After restarting, Trac should show the instances which need a manual upgrade via the automated upgrade scripts to ease the pain. These scripts are run via [TracAdmin trac-admin]:
     38{{{#!sh
    2939trac-admin /path/to/projenv upgrade
    3040}}}
    3141
    32 This command will do nothing if the environment is already up-to-date.
    33 
    34 Note that if you are using a PostgreSQL database, this command will fail with the message that the environment can only be backed up when you use an SQLite database. This means that you will have to backup the repository and the database manually. Then, to perform the actual upgrade, run:
    35 {{{
     42This command will not have any effect if the environment is already up-to-date.
     43
     44Note that a backup of your database will be performed automatically prior to the upgrade.
     45This feature is relatively new for PostgreSQL or MySQL databases, so if it fails, you will have to backup the database manually. Then, to perform the actual upgrade:
     46{{{#!sh
    3647trac-admin /path/to/projenv upgrade --no-backup
    3748}}}
    3849
    39 === Update the Trac Documentation ===
    40 
    41 Every [wiki:TracEnvironment Trac environment] includes a copy of the Trac documentation for the installed version. As you probably want to keep the included documentation in sync with the installed version of Trac, [wiki:TracAdmin trac-admin] provides a command to upgrade the documentation:
    42 {{{
     50=== 4. Update the Trac Documentation === #UpdatetheTracDocumentation
     51
     52By default, every [TracEnvironment Trac environment] includes a copy of the Trac documentation for the installed version. However, to keep the included documentation in sync with the installed version of Trac, use the following [TracAdmin trac-admin] command to upgrade the documentation:
     53{{{#!sh
    4354trac-admin /path/to/projenv wiki upgrade
    4455}}}
    4556
    46 Note that this procedure will of course leave your `WikiStart` page intact.
    47 
    48 === Restart the Web Server ===
    49 
    50 In order to reload the new Trac code you will need to restart your web server (note this is not necessary for [wiki:TracCgi CGI]).
    51 
    52 == Specific Versions ==
    53 
    54 The following sections discuss any extra actions that may need to be taken to upgrade to specific versions of Trac.
    55 
    56 == From 0.9.x to 0.10.x ==
    57 
    58 Due to some changes in the Wiki syntax, you may notice that certain parts of your pages no longer work as expected:
    59  * Previously, links to images would result in that image being embedded into the page. Since 0.10, links to images remain plain links. If you want to embed an image in the page, use the `[[Image]]` macro.
    60  * You can no longer use `%20` in wiki links to encode spaces. Instead, you should quote the name containing spaces (for example, use `wiki:"My page"` instead of `wiki:My%20page`.)
    61 
    62 Several enhancements have been made to the version control subsystem, in particular for the support of scoped repositories has been improved.
    63 It is recommended that you perform a [TracAdmin#InteractiveMode trac-admin] '''`resync`''' operation to take advantage of these improvements.
    64 
    65 Also note that the argument list of the [TracAdmin trac-admin] '''`initenv`''' command has changed: there's a new argument for determining the type of version control system. The old usage was:
    66 {{{
    67    initenv <projectname> <db> <repospath> <templatepath>
    68 }}}
    69 The new usage is:
    70 {{{
    71    initenv <projectname> <db> <repostype> <repospath> <templatepath>
    72 }}}
    73 If you're using any scripts that automate the creation of Trac environments, you will need to update them. If you're using Subversion, specify `svn` for the `<repostype>` argument.
    74 
    75 == From 0.9.3 to 0.9.4 ==
    76 
    77 There is a bug in Pysqlite 1.x that causes reports using the "%" character for `LIKE` clauses or date formatting to fail.  You will need to use escape the percent characters with another: "%%".
    78 
    79 == From 0.9.x to 0.9.3 or later ==
    80 
    81 If you are using plugins you might need to upgrade them. See http://projects.edgewall.com/trac/milestone/0.9.3 for further details.
    82 
    83 == From 0.9-beta to 0.9 ==
    84 
    85 If inclusion of the static resources (style sheets, javascript, images) is not working, check the value of the `htdocs_location` in trac.ini. For [wiki:TracModPython mod_python], [wiki:TracStandalone Tracd] and [wiki:TracFastCgi FastCGI], you can simply remove the option altogether. For [wiki:TracCgi CGI], you should fix it to point to the URL you mapped the Trac `htdocs` directory to (although you can also remove it and then [wiki:TracCgi#MappingStaticResources map the static resources]). If you're still having problems after removing the option, check the paths in the `trac/siteconfig.py` file and fix them if they're incorrect.
    86 
    87 If you've been using plugins with a beta release of Trac 0.9, or have disabled some of the built-in components, you might have to update the rules for disabling/enabling components in [wiki:TracIni trac.ini]. In particular, globally installed plugins now need to be enabled explicitly. See TracPlugins and TracIni for more information.
    88 
    89 If you want to enable the display of all ticket changes in the timeline (the “Ticket Details” option), you now have to explicitly enable that in [wiki:TracIni trac.ini], too:
    90 
    91 {{{
    92 [timeline]
    93 ticket_show_details = true
    94 }}}
    95 
    96 == From 0.8.x to 0.9 ==
    97 
    98 [wiki:TracModPython mod_python] users will also need to change the name of the mod_python handler in the Apache HTTPD configuration:
    99 {{{
    100    from: PythonHandler trac.ModPythonHandler
    101    to:   PythonHandler trac.web.modpython_frontend
    102 }}}
    103 
    104 If you have [http://initd.org/tracker/pysqlite PySQLite] 2.x installed, Trac will now try to open your SQLite database using the SQLite 3.x file format. The database formats used by SQLite 2.8.x and SQLite 3.x are incompatible. If you get an error like ''“file is encrypted or is not a database”'' after upgrading, then you must convert your database file.
    105 
    106 To do this, you need to have both SQLite 2.8.x and SQLite 3.x installed (they have different filenames so can coexist on the same system). Then use the following commands:
    107 {{{
    108  $ mv trac.db trac2.db
    109  $ sqlite trac2.db .dump | sqlite3 trac.db
    110 }}}
    111 
    112 To update multiple database files at once on linux you may use the following command (replace {{{/var/trac}}} withe the location where your trac installtions reside):
    113 {{{
    114  $ find /var/trac/ -iname "trac.db" | xargs -i bash -c "mv {} {}.2; sqlite {}.2 .dump | sqlite3 {};"
    115 }}}
    116 
    117 Remember the give the webserver write permission to trac.db.
    118 
    119 After testing that the conversion was successful, the `trac2.db` file can be deleted. For more information on the SQLite upgrade see http://www.sqlite.org/version3.html.
    120 
    121 == From 0.7.x to 0.8 ==
    122 
    123 0.8 adds a new roadmap feature which requires additional permissions. While a
    124 fresh installation will by default grant ROADMAP_VIEW and MILESTONE_VIEW
    125 permissions to anonymous, these permissions have to be granted manually when
    126 upgrading:
    127 {{{
    128  $ trac-admin /path/to/projectenv permission add anonymous MILESTONE_VIEW
    129  $ trac-admin /path/to/projectenv permission add anonymous ROADMAP_VIEW
    130 }}}
     57Note that this procedure will leave your `WikiStart` page intact.
     58
     59=== 5. Refresh static resources
     60
     61If you have set up a web server to give out static resources directly (accessed using the `/chrome/` URL) then you will need to refresh them using the same command:
     62{{{#!sh
     63trac-admin /path/to/env deploy /deploy/path
     64}}}
     65
     66This will extract static resources and CGI scripts (`trac.wsgi`, etc) from new Trac version and its plugins into `/deploy/path`.
     67
     68Some web browsers (IE, Opera) cache CSS and Javascript files aggressively, so you may need to instruct your users to manually erase the contents of their browser's cache, a forced refreshed (`<F5>`) should be enough.
     69{{{#!comment
     70Remove above note once #9936 is fixed.
     71}}}
     72
     73=== 6. Steps specific to a given Trac version
     74
     75==== Upgrading from Trac 1.0 to 1.2 #to1.2
     76
     77===== Python 2.5 no longer supported
     78
     79Upgrade Python to at least 2.6 or 2.7, but not 3.0 or greater.
     80
     81===== Obsolete Plugins
     82
     83Trac has added functionality equivalent to the following plugins:
     84* [https://trac-hacks.org/wiki/AdminEnumListPlugin AdminEnumListPlugin]
     85* [https://trac-hacks.org/wiki/DateFieldPlugin DateFieldPlugin]: see the **time** [TracTicketsCustomFields#AvailableFieldTypesandOptions custom field type]
     86* [https://trac-hacks.org/wiki/GroupBasedRedirectionPlugin GroupBasedRedirectionPlugin]: the default handler can set as a user preference.
     87* [https://trac-hacks.org/wiki/LinenoMacro LinenoMacro]: see WikiProcessors#AvailableProcessors
     88* [https://trac-hacks.org/wiki/NeverNotifyUpdaterPlugin NeverNotifyUpdaterPlugin]: see [TracNotification#notification-subscriber-section notification subscribers]
     89* [https://trac-hacks.org/wiki/QueryUiAssistPlugin QueryUiAssistPlugin]: see TracQuery#Filters.
     90* [https://trac-hacks.org/wiki/TicketCreationStatusPlugin TicketCreationStatusPlugin]: see [#NewWorkflowActions]
     91
     92The plugins should be removed when upgrading Trac to 1.2.
     93
     94===== New workflow actions #NewWorkflowActions
     95
     96The ticket creation step is controlled with a workflow action. The default workflow has `create` and `create_and_assign` actions. The `create` action will always be added when upgrading the database. The `create_and_assign` action will be added if the workflow has an //assigned// state. You may want to edit your workflow after upgrading the database to customize the actions available on the //New Ticket// page.
     97
     98===== New permissions policy for read-only wiki pages
     99
     100Since 1.1.2 the read-only attribute of wiki pages is enabled and enforced only when `ReadonlyWikiPolicy` is in the list of active permission policies. If `[trac] permission_policy` has the default value `DefaultPermissionPolicy, LegacyAttachmentPolicy`, then `ReadonlyWikiPolicy` should be automatically appended to the list when upgrading the environment:
     101{{{#!ini
     102[trac]
     103permission_policies = ReadonlyWikiPolicy,
     104 DefaultPermissionPolicy,
     105 LegacyAttachmentPolicy
     106}}}
     107
     108If other permission policies are enabled, `trac.ini` will need to have `ReadonlyWikiPolicy` appended to the list of active `permission_policies`. See TracFineGrainedPermissions#ReadonlyWikiPolicy for additional details on the proper ordering.
     109
     110==== Upgrading from Trac 0.12 to Trac 1.0 #to1.0
     111
     112===== Python 2.4 no longer supported
     113
     114Upgrade Python to at least 2.5, but not 3.0.
     115
     116===== Obsolete Plugins
     117
     118Trac has added functionality equivalent to the following plugins:
     119
     120* [https://trac-hacks.org/wiki/BatchModifyPlugin BatchModifyPlugin]
     121* ​[https://trac-hacks.org/wiki/GitPlugin GitPlugin]
     122* [https://trac-hacks.org/wiki/OverrideEditPlugin OverrideEditPlugin]
     123
     124The plugins should be removed when upgrading Trac to 1.0.
     125
     126===== Subversion components not enabled by default for new installations
     127
     128The Trac components for Subversion support are no longer enabled by default. To enable the svn support, you need to make sure the `tracopt.versioncontrol.svn` components are enabled, for example by setting the following in the TracIni:
     129{{{#!ini
     130[components]
     131tracopt.versioncontrol.svn.* = enabled
     132}}}
     133
     134The upgrade procedure should take care of this and change the TracIni appropriately, unless you already had the svn components explicitly disabled.
     135
     136===== Attachments migrated to new location
     137
     138Another step in the automatic upgrade will change the way the attachments are stored. Create a backup of the `attachments` directory before upgrading. In case the `attachments` directory contains some files which are //not// attachments, the last step of the migration to the new layout will fail: the deletion of the now unused `attachments` directory can't be done if there are still files and folders in it. You may ignore this error, but better to move them elsewhere and remove the `attachments` directory manually. The attachments themselves are now all located in your environment below the `files/attachments` directory.
     139
     140===== Behavior of `[ticket] default_owner` changed
     141
     142Prior to 1.0, the owner field of new tickets always defaulted to `[ticket] default_owner` when the value was not empty. If the value was empty, the owner field defaulted to to the Component's owner. In 1.0 and later, the `default_owner` must be set to `< default >` to make new tickets default to the Component's owner. This change allows the `default_owner` to be set to an empty value if no default owner is desired.
     143
     144==== Upgrading from Trac 0.11 to Trac 0.12
     145
     146===== Python 2.3 no longer supported
     147
     148The minimum supported version of Python is now 2.4.
     149
     150===== SQLite v3.x required
     151
     152SQLite v2.x is no longer supported. If you still use a Trac database of this format, you'll need to convert it to SQLite v3.x first. See [trac:PySqlite#UpgradingSQLitefrom2.xto3.x] for details.
     153
     154===== [trac:PySqlite] 2 required
     155
     156[trac:PySqlite] 1.1.x is no longer supported. Please install 2.5.5 or later if possible, see [#Tracdatabaseupgrade Trac database upgrade] below.
     157
     158===== Obsolete Plugins
     159
     160Trac has added functionality equivalent to the following plugins:
     161
     162* [https://trac-hacks.org/wiki/AutoQueryPlugin AutoQueryPlugin]
     163* ​[https://trac-hacks.org/wiki/AdminConsoleProviderPatch AdminConsoleProviderPatch]
     164* [https://trac-hacks.org/wiki/AnchorMacro AnchorMacro]: see WikiFormatting#SettingAnchors
     165* [https://trac-hacks.org/wiki/TicketChangePlugin TicketChangePlugin]: see [TracPermissions#TicketSystem TICKET_EDIT_COMMENT permission]
     166* [https://trac-hacks.org/wiki/TicketDeletePlugin TicketDeletePlugin]: see `tracopt.ticket.deleter`
     167* [https://trac-hacks.org/wiki/SubversionLocationPlugin SubversionLocationPlugin]: see TracRepositoryAdmin#Repositories
     168* [https://trac-hacks.org/wiki/WikiCreoleRendererPlugin WikiCreoleRendererPlugin]: see [trac:WikiCreole]
     169* [https://trac-hacks.org/wiki/RepoRevisionSyntaxPlugin RepoRevisionSyntaxPlugin] (added in 0.12.1)
     170
     171The plugins should be removed when upgrading Trac to 0.12.
     172
     173===== Multiple Repository Support
     174
     175The latest version includes support for multiple repositories. If you plan to add more repositories to your Trac instance, please refer to TracRepositoryAdmin#Migration.
     176
     177This may be of interest to users with only one repository, since there is now a way to avoid the potentially costly resync check at every request.
     178
     179===== Resynchronize the Trac Environment Against the Source Code Repository
     180
     181Each [TracEnvironment Trac environment] must be resynchronized against the source code repository in order to avoid errors such as "[trac:#6120 No changeset ??? in the repository]" while browsing the source through the Trac interface:
     182
     183{{{#!sh
     184trac-admin /path/to/projenv repository resync '*'
     185}}}
     186
     187===== Improved repository synchronization
     188
     189In addition to supporting multiple repositories, there is now a more efficient method for synchronizing Trac and your repositories.
     190
     191While you can keep the same synchronization as in 0.11 adding the post-commit hook as outlined in TracRepositoryAdmin#Synchronization and TracRepositoryAdmin#ExplicitSync will allow more efficient synchronization and is more or less required for multiple repositories.
     192
     193Note that if you were using the `trac-post-commit-hook`, ''you're strongly advised to upgrade it'' to the new hook documented in the above references and [TracWorkflow#Howtocombinethetracopt.ticket.commit_updaterwiththetestingworkflow here], as the old hook will not work with anything else than the default repository and even for this case, it won't trigger the appropriate notifications.
     194
     195===== Authz permission checking
     196
     197The authz permission checking has been migrated to a fine-grained permission policy. If you use authz permissions (aka `[trac] authz_file` and `authz_module_name`), you must add `AuthzSourcePolicy` in front of your permission policies in `[trac] permission_policies`. You must also remove `BROWSER_VIEW`, `CHANGESET_VIEW`, `FILE_VIEW` and `LOG_VIEW` from your global permissions with `trac-admin $ENV permission remove` or the "Permissions" admin panel.
     198
     199===== Microsecond timestamps
     200
     201All timestamps in database tables, except the `session` table, have been changed from "seconds since epoch" to "microseconds since epoch" values. This change should be transparent to most users, except for custom reports. If any of your reports use date/time columns in calculations (e.g. to pass them to `datetime()`), you must divide the values retrieved from the database by 1'000'000. Similarly, if a report provides a calculated value to be displayed as a date/time (i.e. with a column named "time", "datetime", "changetime", "date", "created" or "modified"), you must provide a microsecond timestamp, that is, multiply your previous calculation with 1'000'000.
     202
     203==== Upgrading from Trac 0.10 to Trac 0.11
     204
     205===== Site Templates and Styles
     206
     207The templating engine has changed in 0.11 to Genshi, please look at TracInterfaceCustomization for more information.
     208
     209If you are using custom CSS or modified templates in the `templates` directory of the TracEnvironment, you will need to convert them to the Genshi way of doing things. To continue to use your style sheet, follow the instructions at TracInterfaceCustomization#SiteAppearance.
     210
     211===== Trac Macros, Plugins
     212
     213The Trac macros will need to be adapted, as the old-style wiki-macros are not supported anymore due to the drop of [trac:ClearSilver] and the HDF. They need to be converted to the new-style macros, see WikiMacros. When they are converted to the new style, they need to be placed into the plugins directory instead and not wiki-macros, which is no longer scanned for macros or plugins.
     214
     215===== For FCGI/WSGI/CGI users
     216
     217For those who run Trac under the CGI environment, run this command in order to obtain the trac.*gi file:
     218{{{#!sh
     219trac-admin /path/to/env deploy /deploy/directory/path
     220}}}
     221
     222This will create a deploy directory with the following two subdirectories: `cgi-bin` and `htdocs`. Then update your Apache configuration file `httpd.conf` with this new `trac.cgi` location and `htdocs` location.
     223
     224===== Web Admin plugin integrated
     225
     226If you had the [trac:WebAdmin] plugin installed, you can uninstall it as it is part of the Trac code base since 0.11.
     227
     228===== New Default Configurable Workflow
     229
     230When you run `trac-admin <env> upgrade`, your `trac.ini` will be modified to include a `[ticket-workflow]` section. The workflow configured in this case is the original workflow, so that ticket actions will behave like they did in 0.10:
     231
     232{{{#!Workflow width=500 height=240
     233leave = * -> *
     234leave.operations = leave_status
     235leave.default = 1
     236accept = new -> assigned
     237accept.permissions = TICKET_MODIFY
     238accept.operations = set_owner_to_self
     239resolve = new,assigned,reopened -> closed
     240resolve.permissions = TICKET_MODIFY
     241resolve.operations = set_resolution
     242reassign = new,assigned,reopened -> new
     243reassign.permissions = TICKET_MODIFY
     244reassign.operations = set_owner
     245reopen = closed -> reopened
     246reopen.permissions = TICKET_CREATE
     247reopen.operations = del_resolution
     248}}}
     249
     250There are some significant caveats in this, such as accepting a ticket sets it to 'assigned' state, and assigning a ticket sets it to 'new' state. So you will probably want to migrate to "basic" workflow; [trac:source:trunk/contrib/workflow/migrate_original_to_basic.py contrib/workflow/migrate_original_to_basic.py] may be helpful. See TracWorkflow for a detailed description of the new basic workflow.
     251
     252=== 7. Restart the Web Server #RestarttheWebServer
     253
     254If you are not running [wiki:TracCgi CGI], reload the new Trac code by restarting your web server.
     255
     256== Known Issues
     257
     258=== Customized Templates
     259
     260Trac supports customization of its Genshi templates by placing copies of the templates in the `<env>/templates` folder of your [TracEnvironment environment] or in a common location specified in the [[TracIni#GlobalConfiguration| [inherit] templates_dir]] configuration setting. If you choose to do so, be aware that you will need to repeat your changes manually on a copy of the new templates when you upgrade to a new release of Trac (even a minor one), as the templates will likely evolve. So keep a diff around.
     261
     262The preferred way to perform TracInterfaceCustomization is to write a custom plugin doing an appropriate `ITemplateStreamFilter` transformation, as this is more robust in case of changes: we usually won't modify element `id`s or change CSS `class`es, and if we have to do so, this will be documented in the [trac:TracDev/ApiChanges] pages.
     263
     264=== !ZipImportError
     265
     266Due to internal caching of zipped packages, whenever the content of the packages change on disk, the in-memory zip index will no longer match and you'll get irrecoverable !ZipImportError errors. Better anticipate and bring your server down for maintenance before upgrading.
     267See [trac:#7014] for details.
     268
     269=== Wiki Upgrade
     270
     271`trac-admin` will not delete or remove default wiki pages that were present in a previous version but are no longer in the new version.
     272
     273=== Trac database upgrade
     274
     275A known issue in some versions of [trac:PySqlite] (2.5.2-2.5.4) prevents the trac-admin upgrade script from successfully upgrading the database format. It is advised to use either a newer or older version of the sqlite python bindings to avoid this error. For more details see ticket [trac:#9434].
     276
     277=== Parent dir
     278
     279If you use a Trac parent env configuration and one of the plugins in one child does not work, none of the children will work.
     280
     281== Related topics
     282
     283=== Upgrading Python
     284
     285Upgrading Python to a newer version will require reinstallation of Python packages: Trac itself of course, but also [http://pypi.python.org/pypi/setuptools easy_install], if you've been using that. If you are using Subversion, you'll also need to upgrade the Python bindings for svn.
     286
     287==== Windows and Python 2.6
     288
     289If you've been using !CollabNet's Subversion package, you may need to uninstall that in favor of [http://alagazam.net/ Alagazam], which has the Python bindings readily available, see [trac:TracSubversion]. That package works without tweaking.
     290
     291=== Changing Database Backend
     292
     293The [https://trac-hacks.org/wiki/TracMigratePlugin TracMigratePlugin] on [https://trac-hacks.org trac-hacks.org] has been written to assist in migrating between SQLite, MySQL and PostgreSQL databases.
     294
     295=== Upgrading from older versions of Trac #OlderVersions
     296
     297For upgrades from versions older than Trac 0.10, refer first to [trac:wiki:0.10/TracUpgrade#SpecificVersions].
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