ejabberd hard crash and caps_features.DAT showing as not a valid file

We had a hard, nasty crash of the VM running Ejabber.

So, we ended up copying all the files in /var/lib/ejabberd to an earlier cloned image of this same machine.

But ejabberd wouldn’t start with ejabberdctl start. It threw this initially:



{error_logger,{{2015,3,5},{21,25,9}},"Error when reading /var/lib/ejabberd/.erlang.cookie: eacces",[]}


Ultimately, the solution to that problem was found in restoring ownership of the /var/lib/ejabberd/.erlang.cookie to ejabber_user:ejabber_user.

Then, another problem came up, and the only way we found what it was was by running ejabberctl live and watching the output. Here was the output:



** FATAL ** {error,{"Cannot open dets table",caps_features,

[{file,"/var/lib/ejabberd/caps_features.DAT"},


Well, after opening up this file and comparing with another file from an instance that was running, we tried simply renaming it to caps_features.DAT.bak and starting up ejabberd. And it worked.

caps_features.DAT seems to not be critical data – it appears to just be info on clients; and it can be rebuilt over time.