How to edit log message already committed in Subversion?

Essentially you have to have admin rights (directly or indirectly) to the repository to do this. You can either configure the repository to allow all users to do this, or you can modify the log message directly on the server.

See this part of the Subversion FAQ (emphasis mine):

Log messages are kept in the repository as properties attached to each revision. By default, the log message property (svn:log) cannot be edited once it is committed. That is because changes to revision properties (of which svn:log is one) cause the property's previous value to be permanently discarded, and Subversion tries to prevent you from doing this accidentally. However, there are a couple of ways to get Subversion to change a revision property.

The first way is for the repository administrator to enable revision property modifications. This is done by creating a hook called "pre-revprop-change" (see this section in the Subversion book for more details about how to do this). The "pre-revprop-change" hook has access to the old log message before it is changed, so it can preserve it in some way (for example, by sending an email). Once revision property modifications are enabled, you can change a revision's log message by passing the --revprop switch to svn propedit or svn propset, like either one of these:

$svn propedit -r N --revprop svn:log URL 
$svn propset -r N --revprop svn:log "new log message" URL 

where N is the revision number whose log message you wish to change, and URL is the location of the repository. If you run this command from within a working copy, you can leave off the URL.

The second way of changing a log message is to use svnadmin setlog. This must be done by referring to the repository's location on the filesystem. You cannot modify a remote repository using this command.

$ svnadmin setlog REPOS_PATH -r N FILE

where REPOS_PATH is the repository location, N is the revision number whose log message you wish to change, and FILE is a file containing the new log message. If the "pre-revprop-change" hook is not in place (or you want to bypass the hook script for some reason), you can also use the --bypass-hooks option. However, if you decide to use this option, be very careful. You may be bypassing such things as email notifications of the change, or backup systems that keep track of revision properties.

When you run this command,

svn propedit svn:log --revprop -r NNN 

and just in case you see this message:

DAV request failed; it's possible that the repository's pre-revprop-change hook either failed or is non-existent

Its because Subversion doesn’t allow you to modify log messages because they are unversioned and will be lost permanently.

Unix-hosted SVN

Go to the hooks directory on your Subversion server (replace ~/svn/reponame with the directory of your repository)

cd ~/svn/reponame/hooks

Remove the extension

mv pre-revprop-change.tmpl pre-revprop-change

Make it executable (cannot do chmod +x!)

chmod 755 pre-revprop-change

Source

Windows-hosted SVN

The template files in the hooks directory cannot be used as they are Unix-specific. You need to copy a Windows batch file pre-revprop-change.bat to the hooks directory, e.g. the one provided here.

Here's a handy variation that I don't see mentioned in the faq. You can return the current message for editing by specifying a text editor.

svn propedit svn:log --revprop -r N --editor-cmd vim

svnadmin setlog /path/to/repository -r revision_number --bypass-hooks message_file.txt

If your repository enables setting revision properties via the pre-revprop-change hook you can change log messages much easier.

svn propedit --revprop -r 1234 svn:log url://to/repository

Or in TortoiseSVN, AnkhSVN and probably many other subversion clients by right clicking on a log entry and then 'change log message'.

I found a nice implementation of the server side pre-rev-prop-change hook at the svnforum: https://www.svnforum.org/forum/opensource-subversion-forums/scripts-contributions/8571-pre-revprop-change-shell-script-allows-commiters-to-change-own-log-within-x-hours

It implements

• user checking, that is only own commit messages can be edited.
• Svn admin override; admin can edit anything.
• time stamp comparison: only commits that are younger than certain time can be edited

Grab it from there and edit at will. I'd rather not copy it here since I am not the original author and there is no copyright notice that would allow me to do it.

My version of the pre-revprop-change batch script with locale-independent time comparison. I'm using a PowerShell call here, which seems to flash a window in some cases and adds a noticeable delay.

@ECHO OFF

set reposPath=%1
set rev=%2
set user=%3
set propName=%4
set action=%5

::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
:: Only allow changes to svn:log. The author, date and other revision
:: properties cannot be changed
::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
if /I not '%propName%'=='svn:log' goto ERROR_PROPNAME

::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
:: Only allow modifications to svn:log (no addition/overwrite or deletion)
::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
if /I not '%action%'=='M' goto ERROR_ACTION

::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
:: Only allow user to modify their own log messages
::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
set author=
for /f "delims=" %%a in ('svnlook author -r %rev% %reposPath%') do set author=%%a

if /I not '%author%'=='%user%' goto ERROR_WRONGUSER

::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
:: Only allow user to modify log messages from today, old messages locked down
::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
set minDate=
set revDate=
set revDateStr=
for /f "delims=" %%a in ('svnlook date -r %rev% %reposPath%') do set revDateStr=%%a

:: Expects revDateStr in the format: 2012-02-24 ...
:: https://svnbook.red-bean.com/en/1.7/svn.ref.svnlook.c.date.html
for /F "tokens=1-3 delims=- " %%a in ("%revDateStr%") do set revDate=%%a%%b%%c
:: Note that PowerShell calls like this can be slow and a window can show up while they run.
for /f %%i in ('"powershell (Get-Date).AddDays(-1).ToString(\"yyyyMMdd\")"') do set minDate=%%i
if "%revDate%" LSS "%minDate%" goto ERROR_MSGTOOOLD

::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
:: Make sure that the new svn:log message contains some text.
::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
set bIsEmpty=true
for /f "tokens=*" %%g in ('find /V ""') do set bIsEmpty=false
if '%bIsEmpty%'=='true' goto ERROR_EMPTY

goto :eof

:ERROR_EMPTY
echo Empty svn:log properties are not allowed. >&2
goto ERROR_EXIT

:ERROR_PROPNAME
echo Only changes to svn:log revision properties are allowed. >&2
goto ERROR_EXIT

:ERROR_ACTION
echo Only modifications to svn:log revision properties are allowed. >&2
goto ERROR_EXIT

:ERROR_WRONGUSER
echo You are not allowed to modify other user's log messages. >&2
goto ERROR_EXIT

:ERROR_MSGTOOOLD
echo You are not allowed to modify log messages that are too old (2+ days). >&2
goto ERROR_EXIT

:ERROR_EXIT
exit /b 1

Sources: original version of the script, previous answer, PowerShell example