Is there a way to track down the source (codeline) of the problem by some "debug" mode of DW?No, but you can modify the source of course.
That's probably out of my PHP knowledge...
However since you getting "blank pages" I recommend to read http://www.dokuwiki.org/faq:blankpage
That doesn't help. DokuWiki is otherwise running fine and as I wrote initially, there are no errors in the Apache logfile.
Anything that could help with the "The plugin manager was unable to decompress the downloaded file" error message? Where does the DW plugin manager download the plugin files?
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