Like it or not, many SEOs use the disavow backlinks feature within Google which launched in 2012 mostly based on webmaster feedback.
But sometimes the disavow file can cause a headache for webmasters. When you have weird characters in your URLs, sometimes Google can confuse them and not disavow them or show errors.
John Mueller of Google responded to one such complaint with advice on how to test it. He said on Twitter to "try to submit a file with just that line, then rewrite the line." Use this method to check which URLs are causing you problems and then fix them one by one. Sounds like this method can take some time with debugging but I don't know if there are any better ways?
He added that "sometimes special characters are tricky" for Google's disavow system to handle.
Forum discussion at Twitter.
