It's not in utf. When I encode it like you told me, it can't find the file anymore (the ë now changed to an utf sequence when I print the variable, and the filesystem doesn't like utf filenames). Both strings seem to be iso-8859-1, probably just plain 8bit. When I update it to utf, though, it's the DOT it doesn't want to match on - not the umlaut.

/^([\w\s.]+)$/ # unescaped
/^([\w\s\.]+)$/ # or escaped
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Is there something wrong with the dot in the regex?