WebGL Build doesn't work on hosted websites with Firefox

I’m trying to host my WebGL game on a few websites and I get the same error with Firefox:

NotFoundError: The operation failed because the requested database object could not be found. For example, an object store did not exist but was being opened.
IDBFS.getRemoteSet/<()
IDBFS.getDB/req.onsuccess()

The game works fine with firefox when playing locally. I’m using Unity 5.3.5p6. I’m stumped I’ve seen this problem a few places but I haven’t been able to find a solution.

Are you sure you haven’t renamed any files and actually included all files from the build directory? Keep in mind that most webservers run linux and like most unix / linux based systems the file system is case sensitive. So “Test.txt” is not the same as “text.txt” or “Test.TXT”. The same applied to folder names.

Apart from that make sure your webserver config does not restrict access to certain required folders / files.