So on an existing SharePoint Farm with a STATIC activiation key, I'm setting up a quick demo. Create a new site, all good. Edit the home page then try to publish and I get:
The trial period for this product has expired
Odd for sure - particularly with a Static key (which never expires). Since this farm has been running for quite some time, naturally, we looked into changes - other than a few recent updates (and don't you hate MS likes to stick a few for SharePoint in there?) nothing clear.
After much research, you can easily find a workaround for an actual Trial (with a new key):
But this was obviously not our issue. The only 'change' was a rebuild of the search service - maybe the cause? Don't know...
However, finally found the fix using the PSConfig command - simply opening SharePoint 2013 Management Shell (running as Administrator!), ran the following:
PSConfig -cmd secureresources
After a bit, the process completed (took about 15 minutes):
Right after this, ran and IISReset and Viola - SharePoint 'all better'.
** Some folks said that running an IISReset is all that is required afterwards HOWEVER, in a multi-farm enviornment two other things may be required:
1) PSConfig should be run on all SharePoint Servers
2) A reboot MAY be required of the entire farm
Needless to say, if this happens, just hope you got an outage window handy!