500 error "Uncaught Error: Class '\XF\App' not found"

Question

From yesterday evening I've got a fatal error on my site and I've seen in Error Log file that error:

[15-Feb-2020 13:40:22 UTC] PHP Fatal error:  Uncaught Error: Class '\XF\App' not found in /home/stealths/public_html/src/XF.php:361
Stack trace:
#0 /home/stealths/public_html/src/XF.php(352): XF::setupApp('\\XF\\App')
#1 /home/stealths/public_html/src/XF.php(169): XF::app()
#2 [internal function]: XF::handleException(Object(Error))
#3 {main}
thrown in /home/stealths/public_html/src/XF.php on line 361

I don't know what I can do to resolve this problem.

Answer 1

It looks like you posted this question on multiple websites, and have already received an answer on one of them. I'll cross-post the answer made by Mike, a XenForo developer who posted on the XenForo Forums for future potential readers.

It looks like the files haven't been uploaded properly. I'd reupload all of the XF files.