I am working on my PhD thesis and have a huge file to compile. In the package file, I included the following package and commented chapter by chapter but still, I get this error. I'll appreciate if you can help me to solve this issue. I am compiling by pdflatex and using the BibTeX for the bibliography.


P.s. error is about this character (â) but I do not have this character in my file.

Package ucs Error: Unknown Unicode character 128 = U+0080,
(ucs)                possibly declared in uni-0.def.
(ucs)                Type H to see if it is available with options.
  • Since biblatex (note the la, not BibTeX) is incompatible with utfx/ucs it is unlikely that you are using it, so I removed the tag and replaced it with the more generic bibliographies tag. U+0080 is not a printable Unicode char, it seems something went wrong in your encoding. Is your .bib file maybe encoded in Latin-1? (Cf. stackoverflow.com/q/15271453) Make sure that all files involved have the same encoding (ideally UTF-8). Usually it is enough to use utf8 instead of utf8x nowadays, so I'd use only utf8 if possible. – moewe Mar 27 '19 at 9:28
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    I would use the standard utf8 option rather than utf8x (actually inputenc isn't needed at all with recent releases) but character 128 is an undefined control character in Unicode, it is not â which is U+00E2 make sure your file is saved in UTF-8 encoding – David Carlisle Mar 27 '19 at 9:28
  • @moewe, I changed it to utf8 but still, I get the error. Same error even points to a line that is commented. – AmiDel Mar 27 '19 at 9:37
  • If the encoding of one of your files is wrong, a change from utf8x to utf8 was unlikely to resolve the issue, but it was a good idea nonetheless. Double-check the reported line in the raw .log file. In case several different files are involved it may well be that a line number does not refer to the main .tex file, but to a different included or auxiliary file. You can find out which file the message refers to by tracking parentheses in the .log, see David's answer in tex.stackexchange.com/q/481423/35864. – moewe Mar 27 '19 at 9:40
  • @moewe I went through the .log file and trace all the chapters but no error printed in the log file. – AmiDel Mar 27 '19 at 10:10

I had this problem and just solved it. Couldn't display the weird "pad" character in Atom or anything so I couldn't delete it easily. However, I deleted and manually retyped the section of the paragraph that it was in. Then, my TeX file compiled with no errors. So not a bug, there literally was a U+0080 somewhere in the file.

More detail: I have no idea how this "pad" character U+0080 was inserted. For some reason one of my two dozen TeX source files (chapters, front matter, and back matter are all separate files) was throwing this error that it couldn't parse U+0080. I opened the offending file and it said it was in ISOLatin9, instead of UTF-8 as expected. I resaved as UTF-8. Still gave the error when recompiling. I deleted and retyped the sentence that supposedly had the character and it compiled successfully. So it did literally have the U+0080 character in there, but I have no idea how one of a dozen TeX files ends up with this problem.

  • Please check if your file maybe used to contain a euro sign "€" which is missing now. If your file actually was Windows-1252 encoded and you converted it from Latin9 to UTF-8, all euro signs would be converted to U+0080. – Marcel Krüger Oct 28 '19 at 7:01
  • This was almost certainly it. – Nycto Oct 30 '19 at 16:42

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