This erorr came again when I recompile 'thesis.tex' in another computer

[WhiteDLee]

Running 'thesis.tex' using TeXworks.

Some errors occurred

newtxmath.sty
783
LaTeX Error: Command `\lvert' already defined.

See the LaTeX manual or LaTeX Companion for explanation.
Type H for immediate help.
...

l.783 ...thopen} {symbols}{106}{largesymbols}{12}

newtxmath.sty
784
LaTeX Error: Command `\rvert' already defined.

See the LaTeX manual or LaTeX Companion for explanation.
Type H for immediate help.
...

l.784 ...thclose} {symbols}{106}{largesymbols}{12}

newtxmath.sty
785
LaTeX Error: Command `\lVert' already defined.

See the LaTeX manual or LaTeX Companion for explanation.
Type H for immediate help.
...

l.785 ...thopen} {symbols}{107}{largesymbols}{13}

newtxmath.sty
786
LaTeX Error: Command `\rVert' already defined.

See the LaTeX manual or LaTeX Companion for explanation.
Type H for immediate help.
...

l.786 ...thclose} {symbols}{107}{largesymbols}{13}

[mohuangrui]

1. Check https://github.com/mohuangrui/ucasthesis/wiki/%E7%BC%96%E8%AF%91%E6%8C%87%E5%8D%97

   1. Do not modify uncasthesis before your compilation.
   2. Use xelatex rather than pdflatex
   3. Read guide carefully and provide your complete log file.

2. Reinstall your LaTeX compiler

3. Update your LaTeX packages.

[WhiteDLee]

Thank you. The problem has been solved by the aid of your advice, use xelatex rather than pdflatex.

[mohuangrui]

I have found the root of your problem. It's likely a bug in the latest newtxmath package, which defines \lVert command that conflicts with amsmath package.

If you insist on using pdflatex, the current solution of this is to revert the update of newtxmath rather than update...or you can remove the newtxmath package...

Anyway, the best solution is to use xelatex!

[WhiteDLee]

I have tried it as you said, uninstalling newtxmath package or uninstalling its parent package newtx. But both did not work. It would occur some other error, such as newtxtext.sty not be found and some others. All in all, if using Pdflatex, the process must compile 'newtx'.

Maybe, installing the older newtx package is a good way, but I failed it since I did not find the road. MikTex console seems not to provide a direct way to install an older version of a package, and I did not find the download link of the previous version in CTAN.

All in all, I have failed to use pdflatex, and xelatex is nice.

Thank you again.