For what it's worth I'd also like to stress the argument that external metadata is very useful when running ubooquity attached to a network storage (such as a NAS, google drive, etc). To read the metadata of a file, ubooquity has to download the entire file, which causes unnecessary bandwidth load when the metadata.opf file exists.

This just bit me too.

I am also getting this.
Opening the dev console shows this when submitting the admin password:

Error: c is undefined
str2rstr_utf8@http://localhost:2203/ubooquity/admin-res/sha256-min.js:10:960
hex_hmac_sha256@http://localhost:2203/ubooquity/admin-res/sha256-min.js:10:165
$scope.submitForm/<@http://localhost:2203/ubooquity/admin-res/password.js:18:57
e/<@http://localhost:2203/ubooquity/admin-res/angular.min.js:130:226
$eval@http://localhost:2203/ubooquity/admin-res/angular.min.js:144:463
$digest@http://localhost:2203/ubooquity/admin-res/angular.min.js:142:39
$apply@http://localhost:2203/ubooquity/admin-res/angular.min.js:145:247
l@http://localhost:2203/ubooquity/admin-res/angular.min.js:97:53
H@http://localhost:2203/ubooquity/admin-res/angular.min.js:101:190
dg/