Sometimes you may be surprised what also gets shown in the source code. And after dealing with Linux boxes for the last 3 decades, with over 15 years of that being directly related to setting up sites, I'm familiar with what a 500 error is...but that is NOT what your image reflected, now is it?
See, THIS is a typical 500 error code response page:
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There was a reason I specifically asked that.
This error
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doesn't tell you much... BUT, when you investigated the source code for the page, it showed you that it was an access denied error for the DB user.... something that you can clearly see is NOT given to you on the displayed error page.
Generally, when folks ask you a very specific question like that... there is a reason behind it.
But feel free to pursue it yourself.... the image that I showed took me about 5 minutes to fix their site... after they had been struggling for quite a while to do so themself.
Because there HAVE been cases in the past when an FTP program didn't successfully upload all the files?
It really depends on if you do a manual installation, or if you used the ACP to upload the files (which is generally more reliable).
Again, there are reasons that you are being asked certain questions... usually it's because whomever is asking them has seen issues with involving their specific line of question in the past.