Hi,
please try again after you're logged in and check if following improves:
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I've no glue what "Your locale C seems not to be a UTF-8 locale, you should fix this if you encounter problems." is.
another point maybe the file-names you are using for your media files. Are you using space characters within ? Spaces will be turned into undelines and this may cause trouble. Just give some example file names to exclude this point.
finally please get a glimpse on the post:
https://forum.dokuwiki.org/thread/8904
br Taggic