I have two similar (as far as I can say) installations of MikTex 2.9+Winedt 10.3 on two Windows 10 machines. When I LaTex a particular file on one machine, it compiles with no problem. On the other machine, however, it gives me the following error message:

! Package inputenc Error: Invalid UTF-8 byte sequence.

See the inputenc package documentation for explanation.
Type  H <return>  for immediate help.

l.129 Lenstra, and Lovász
                          known as the LLL algorithm for lattice reduction

! Undefined control sequence.

The problem seems to be the encoding of "Lovász" but I do not know how to solve it. I have looked at the input encoding documentation but it did not help. I am sure that the LaTeX files are exactly the same, one file on a Google drive. When I look at the bottom of Winedt windows on both machines, bot show UTF-8 encoding.

  • 3
    Can you confirm that the files are indeed encoded in UTF-8 independently with another editor? (Notepad++ comes to mind? Check that the á is properly displayed there.)
    – moewe
    Commented Aug 22, 2018 at 5:21
  • 1
    Can you give a minimal example that I compile on my computer under MikTeX and Windows 10?
    – AndréC
    Commented Aug 22, 2018 at 6:08
  • A short-term fix (not a full solution!): Replace all instances of Lovász with Lov{\'a}sz.
    – Mico
    Commented Aug 22, 2018 at 7:08
  • 2
    If the linebreak in the error is where you show the problem is not the accented a but bad bytes at the space. Commented Aug 22, 2018 at 7:45
  • 2
    To check on David's suspicion copy and paste the entire line Lenstra, and Lovász ... from your .tex file into w3c.github.io/xml-entities/unicode-names.html. If the output mentions any weird characters those could be the reason for the error.
    – moewe
    Commented Aug 22, 2018 at 8:00

1 Answer 1


The root file was UTF-8 encoded but the child file was APC encoded. I used @Mico's suggestion to solve the problem. I still do not know how to save a file with UTF-8 encoding. Anyway, I consider my problem solved by using Mico's suggestion.

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