Editor: TexStudio Latex: MiKTex 2.9

I was trying to add a biblatex file to my document and that workt fine for the first few times. After that the Error:

Package inputenc Error: Keyboard character used is undefined(inputenc) in inputencoding `latin1'. \end

started showing up. After that I tried to remove all the text i had added and also the bib-file but that did not work.

It still creates a pdf that seems ok but I do not want there to be any errors that I might overlook.

Does anyone have an idea how to fix this?

  • Try to isolate where the problem comes from. If the problematic entry is in your bib file, remember that you have to run LaTeX -> Biber -> LaTeX to be sure that everything is updated correctly, since bad characters can live on in temporary files (if you want to be really sure, delete all auxiliary files before recompiling). Other than that we can just repeat what the message says, there is a problematic character somewhere. If you know a bit of computer fu you might be able to search your bib file for non-ASCII chars.
    – moewe
    Dec 28, 2017 at 11:14
  • ... The problematic character could be an accented character or one with umlaut (easy to spot), but it could also be a weird space character (basically impossible to spot with the naked eye), or a non-standard dash, a Cyrillic letter that looks like its Latin counterpart, ...
    – moewe
    Dec 28, 2017 at 11:16
  • @moewe it seems I copied a wierd comma when setting up the bib-file. I replaced it and now it is working. Thank you very much. That was really bothering me. And the Tipp with the temp files also helped. If you want you can make an answer out of it and I will accept it.
    – lightlike
    Dec 28, 2017 at 11:29

1 Answer 1


With inputenc errors that don't give more details about the offending character (in contrast to, say How to find this unicode character U+202F in your LaTeX documents?, Biblatex can't read bib-entry) it is important to isolate the problematic characters (the problematic line in your .tex file, the problematic entry in your .bib file). Even more so because the character that causes the mayhem may be hard to spot with the naked eye. It might be a non-standard space, dash or punctuation character that is virtually indistinguishable from the good character in your editor's font. But of course it could be something easier to spot, a accented character, one with umlauts or other diacritics, a non-ASCII char, ....

One good method to isolate the problem is binary search, where you delete half of your document - make sure not to introduce errors doing that, don't tear environments apart, don't split braced groups - and see if the error persist on recompilation.

You might have to run LaTeX several times until the error disappears if it lives in the temporary files. This is especially important for the bibliography, where you have to run at least LaTeX, Biber, LaTeX to be able to determine whether the error is gone for good. To be really sure you can delete the temporary files (.aux, .bcf, .bbl, ...) between compilcations.

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