Run `texdoc errorlog`, or visit http://mirrors.ctan.org/info/knuth-pdf/errata/errorlog.pdf — published as Chapter 11 ("The error log of TeX") of the book (collection of papers) Literate Programming (https://cs.stanford.edu/~knuth/lp.html), and it best makes sense if you also read the previous Chapter 10 "The errors of TeX" (DOI 10.1002/spe.4380190702, https://yurichev.com/mirrors/knuth1989.pdf).
Run `texdoc errorlog`, or visit http://mirrors.ctan.org/info/knuth-pdf/errata/errorlog.pdf — published as Chapter 11 ("The error log of TeX") of the book (collection of papers) Literate Programming (https://cs.stanford.edu/~knuth/lp.html), and it best makes sense if you also read the previous Chapter 10 "The errors of TeX" (DOI 10.1002/spe.4380190702, https://yurichev.com/mirrors/knuth1989.pdf).