I keep getting mysterious errors from RCS

Foswiki can be configured to use RCS for the management of revision histories. RCS is very mature and stable, but on occasion it can cause mysterious problems.

If you see an error like this:

Error saving topic
During save of Web.Topic an error was found by the version control system. Please notify your administrator.

RCS: /usr/bin/rcs  -l %FILENAME|F% failed: 

Go back in your browser and save your changes locally.

without any more information about the error, then this indicates a problem with RCS. There might be more information in the Apache error log, but if not, you may have stumbled on a known RCS bug. The RCS man page states:

A catastrophe (e.g. a system crash) can cause RCS to leave behind a semaphore file that causes later invocations of RCS to claim that the RCS file is in use. To fix this, remove the semaphore file. A semaphore file's name typically begins with , or ends with _.

So the first thing to do is to see if you have any of these semaphore files (use the find program on Unix and OSX) and delete them.

If that doesn't help, you can always enable tracing in the lib/Foswiki/Sandbox.pm module. This will cause Foswiki to print out every external command it executes to standard error (the Apache error log). You can then copy and paste these commands into the shell to reproduce the error outside of Foswiki. This is usually sufficient to show where the problem lies.

-- CrawfordCurrie - 25 Jun 2010

Also if you have upgraded from TWiki, don't forget to perform the following steps to unlock any locked RCS files. This is documented in UpgradeGuide#Copy_content_from_non_default_we

• find data -name '*,v' -exec rcs -u -M '{}' \;
• find pub -name '*,v' -exec rcs -u -M '{}' \;

-- GeorgeClark - 25 Jun 2010

Another cause for mysterious RCS errors is if the /tmp directory, (or the location where RCS will attempt to create temporary files) is not writable. Verify that the apache user is able to create and read files in the temporary directory.

-- GeorgeClark - 06 Jun 2013