After installing OMV Extras, the webUI went blank so I restarted Chrome and now I can not get back into OMV, The password prompt is does not pop up.
This is an absolute nightmare. PLEASE HELP!
I recently had a similar issue. If you know how, ssh in to the machine (I use putty for this). I used the command omv-update and it fixed itself. Hopefully it works for you as well.