Redmine

You can see the version you are using under Administration/Information. Just click on the administration link, then on the information link.

Not seeing any "administration" link. Update please? (Screenshot attached.)

Hi,
You need to have administrator permission to see administration.

It does seem a bit restrictive to stop non-admins from knowing the version of Redmine. I wonder if this was policy or happen-stance.
As non-administrator the best you can do is narrow it down to the year of release by looking at the copyright date in the bottom-right corner.
From this I can see that (at time of writing) this redmine.org version is at least a year old. I would like to see the "Powered by Redmine" footer include the version, but having thought about it for a few moments I realise there is a security argument that this would make it easy for malware bots to search for unpatched instances of Redmine running versions with known vulnerabilities.
You can sometimes also narrow down the version a bit more by looking for features or behaviours that only began from a certain version, although the OP was facing the converse problem of finding out why the expected behaviour was not present.

Good reasoning, @GrahamMcArdle. But of course as you know, every time we rationalize security-by-obscurity, somewhere a fairie dies. Worse than breaking a pinkie promise.