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Suffering with compilation using TeXMaker. I added an external .bib file to add to my thesis, and the resulting changes give me the following error upon compilation (PdFLaTeX + quick view):

! Package inputenc Error: Unicode character ̈ (U+0308)(inputenc) not set up for use with LaTeX.See the inputenc package documentation for explanation.Type H <return> for immediate help....

Strangely enough, the resulting PDF is built in my directory with no visible issues.. any clue what is going on? I have made sure to encode any umlauts, etc. correctly in my bibliography file (e.g. as {\"u}, etc.).

kalle
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    This is likely a case in which a "weird invisible character" is in your bib file, probably from copying and pasting internet stuff (e. g. author names, title of books, abstracts). Proposal: Remove each citation one by one until you find the problem-causing entry (entries). – Dr. Manuel Kuehner May 31 '22 at 01:31
  • For further help, I suggest you create an MWE following this post: https://tex.meta.stackexchange.com/questions/4407 – Dr. Manuel Kuehner May 31 '22 at 01:33
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    I think that's the ticket - thanks Dr. Kuehner. Tedious but necessary work! – kalle May 31 '22 at 02:29
  • U+308 is COMBINING DIAERESIS ... So look for a stray umlaut, and perhaps not your regular äöü one ... – Ingmar May 31 '22 at 03:23
  • I don't use TeXMaker, so I don't know if this is actually possible, but with the editor I do use (emacs), it's possible to "pick up" the reported character from the log, then use it as a search argument in the file. (It's not even necessary to know what the offending character is or means; a match is unambiguous proof.) This is very much quicker than the "divide and conquer" method, although if the search attempt fails, "divide and conquer" is still available. – barbara beeton May 31 '22 at 03:31
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    You could try something like \DeclareUnicodeCharacter{0308}{XXX HERE I AM XXX}. This will suppress the error and will make the "XXX HERE I AM XXX" appear in the document where the offending character appeared. This should help you find the problematic passage/.bib entry. – moewe May 31 '22 at 04:25
  • @moewe That's super smart. You should convert this to an answer. – Dr. Manuel Kuehner May 31 '22 at 06:30
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    See also https://tex.stackexchange.com/q/552489/35864 – moewe May 31 '22 at 15:24

2 Answers2

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(Converting Comment to Answer)

  • This is likely a case in which a "weird invisible character" is in your bib file, probably from copying and pasting stuff from the internet (e. g. author names, title of books, abstracts).
  • Proposal: Remove each citation one by one until you find the problem-causing entry (entries).
Dr. Manuel Kuehner
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One simple way to find out which entry is responsible for the error is to give the Unicode character in question a definition that can easily be searched for in the output. For example something like

\DeclareUnicodeCharacter{0308}{XXX HERE I AM XXX ???}

Then search for "XXX" or "???" in the resulting PDF. (Keep in mind that some PDF readers may have problem finding words if they are hyphenated. So I usually prefer stuff like "XXX" and "???" that is unusual enough and will probably not be hyphenated.)

A common issue with Biber and non-ASCII characters are constructions involving (dotless) is (the letter i without a dot). See Unicode -(U+301) error in biblatex, but not in main text: {\'{\i}}. So if I were you, I'd probably look for that first. Maybe you have \"{\i} somewhere in your .bib file. For Biber that should be \"{i} or even better just ï.

Dr. Manuel Kuehner
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moewe
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