I suspect I have a corrupt plugin actually...
I installed 6 or 7 new plugins on my test hudson and now I'm lost most of the previously installed and working plugins.
Not sure if hudson version itself also auto upgraded one me or not... I think it did...
Either way, is there anyway to determine which plugin or plugin upgrade is the culprit?
I'm on 1.395 (that is as far as it will let me auto-upgrade too) I also downgrade a few times to see if that fixed anything and then upgraded back up using the buttons... No change. Since the problem it has reported a boat load of data files it can not read, when previously there were none.
Primary missing plugins are maven, violations and it many linked plugins.
Check the log files in %HUDSON_HOME%/hudson.err.log and %HUDSON_HOME%/hudson.out.log, if you see some exceptions, see which plugin is throwing them. Delete that plugin, while hudson is stopped. You can delete the dir and the .hpi file from %HUDSON_HOME%/plugins. You may be able to just redownload that plugin, but I would test your server without it first.