Thread:Project:Support desk/Update previous MW 1.16.5 to 1.17.0 throws an 500 internal server error/reply (2)

It'd help to know what the error was that the web installer threw. The debug.txt file is generally not very important for 500 errors (honestly, it almost never contains useful information unless you're a mediawiki programmer). More important is making sure that php displays errors (Its best to set that setting in your php.ini file if possible). Also check your apache error log too (If it was a very plain black writing on white background 500 error, it could be an apache issue, although that'd be weird)

However, the fastest way to fix the problem would be to try to run the update.php script from the command line if possible

The localisationCache issue 213.227.166.119 posted is totally different from your issue. I'm very doubtful they have anything to do with each other.