[19:14:24] [Client thread/WARN] [MCEF]: Could not load file listing; trying to overwrite...
[19:14:24] [Client thread/INFO] [MCEF]: Checking for missing resources...
[19:14:25] [Client thread/INFO] [MCEF]: Found 6 missing resources. Downloading...
[19:14:26] [Client thread/ERROR] [MCEF]: Couldn't download locales.zip! HTTP response is 404; trying with another mirror.
[19:14:26] [Client thread/INFO] [MCEF]: Selected mirror: Ruinscraft MCEF Mirror
[19:14:26] [Client thread/ERROR] [MCEF]: Couldn't download locales.zip! All mirrors seems broken.
[19:14:26] [Client thread/WARN] [MCEF]: Going in virtual mode; couldn't download resources.

Friendly heads up, I found a temporary solution to this exact problem, I just didn't realize it was this problem until I'd already started documenting it in the white screens issue thread. TLDR version, the mirror has the files that should be inside locales.zip instead of locales.zip, for 1.31-Win64.

I've detailed this all in the thread about white screens (caused in my case by the missing locales.zip breaking the installation), but you can download a fix here. Just unzip it into .minecraft/jcef.

If after you do this, and set B:skipUpdates=true in .minecraft/config/mcef.cfg, without which it will keep complaining about the missing zip file, you get a crash complaining about missing dependencies, make sure your launcher is using the full path to java ("C:\yada\yada\javaw.exe" instead of just "javaw.exe"), if you're on windows.

If you don't want to trust an unofficial zip, perfectly understandable, so here's a list to all the files I expect you'll need to download from the official mirror to make a fix of which you can trust the origin. It's tedious to download fifty-someodd files individually, but it does work! You can cross-reference my list with the 1.31 Windows section of .minecraft/jcef/mcef2.json, to see if you're missing anything I wasn't. The files on my list that aren't in mcef2.json are all the files that are on the mirror for 1.31/win64, but aren't in the remote config file that becomes mcef2.json, presumably because they should be in the missing locales.zip.

Note that /1.31/win64/ in the mirror urls in my list corresponds to the .minecraft/jcef directory, so the 2 .bin files need to be in .minecraft/jcef, the 2 .dll's in jcef/swiftshader, and all the locale .pak files in jcef/locales, assuming you too are missing the bin and swiftshader/*dll files.

Friendly heads up, I found a temporary solution to this exact problem, I just didn't realize it was this problem until I'd already started documenting it in the white screens issue thread. TLDR version, the mirror has the files that should be inside locales.zip instead of locales.zip, for 1.31-Win64.

I've detailed this all in the thread about white screens (caused in my case by the missing locales.zip breaking the installation), but you can download a fix here. Just unzip it into .minecraft/jcef.

If after you do this, and set B:skipUpdates=true in .minecraft/config/mcef.cfg, without which it will keep complaining about the missing zip file, you get a crash complaining about missing dependencies, make sure your launcher is using the full path to java ("C:\yada\yada\javaw.exe" instead of just "javaw.exe"), if you're on windows.

If you don't want to trust an unofficial zip, perfectly understandable, so here's a list to all the files I expect you'll need to download from the official mirror to make a fix of which you can trust the origin. It's tedious to download fifty-someodd files individually, but it does work! You can cross-reference my list with the 1.31 Windows section of .minecraft/jcef/mcef2.json, to see if you're missing anything I wasn't. The files on my list that aren't in mcef2.json are all the files that are on the mirror for 1.31/win64, but aren't in the remote config file that becomes mcef2.json, presumably because they should be in the missing locales.zip.

Note that /1.31/win64/ in the mirror urls in my list corresponds to the .minecraft/jcef directory, so the 2 .bin files need to be in .minecraft/jcef, the 2 .dll's in jcef/swiftshader, and all the locale .pak files in jcef/locales, assuming you too are missing the bin and swiftshader/*dll files.

lts work thank you!