# Fix the L3 Programming Layer Error in Bookdown

Hongtao Hao / 2020-12-16

I updated two of my Bookdown projects but found that I was not able to compile the LaTeX. The warning message says:

! LaTeX3 Error: Mismatched LaTeX support files detected.

The L3 Programming layer in the LaTeX format is dated 2020-12-03, but in your TeX tree the files require at least 2020-12-07.

As follows:

I found the solution in Yihui’s TinyTeX documentation .

Open a new R Script, and input the following two lines of codes:

library(tinytex)
tlmgr_update()


The above error might be due to expl3’s update on 2020-12-07.

Hope it helps.