So the link contains %C3%A4 instead of ä in the URL? This would be correct. That’s the correct escape sequence for the German umlaut ä when using UTF8.
You have to double check the formatting of the URL using the developer tools of your browser, because some browsers (like chrome) won’t display %C3%A4 in the address bar although that is the URL that is used when requesting the resource from the server.
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