Firefox: login stuck at 'Loading, please wait...'

My virgin installation of Firefox 54 (portable) on Windows 7 refuses to load ttrss. The login process gets stuck at ‘Loading, please wait…’. There’s no usual blue progress bar, just black letters on white background. What may cause this?

Have you checked the console logs?

wtf is virgin installation? git? something else? f12 browser console? httpd logs?

‘Virgin’ means pristine: no extensions or other cruft to interfere with tt-rss.
The Firefox console reports:

TypeError: _374 is undefined  tt-rss-layer.js:8:95296
Use of getAttributeNode() is deprecated. Use getAttribute() instead.  dojo.js:8:93772

Eh?

I have been using Firefox Nightly on a Windows and a Linux box for years using tt-rss and it works fine for me. I have done clean install of Firefox and all seems to work just fine.

Solved. Same issue as here. Setting a language in Firefox helped.

So the virgin installation was not that virgin after all?

tt-rss maybe, firefox seemingly not so much

Probably not. Unless Firefox installs out-of-the-box with languages.