This is e-upTeX, Version 3.14159265-p3.8.3-u1.26-191112-2.6 (utf8.uptex) (TeX Live 2020) (preloaded format=uplatex 2020.4.26)  5 FEB 2024 14:24
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**chatsystem.tex
(./chatsystem.tex
pLaTeX2e <2020-02-02u03>+3 (based on LaTeX2e <2020-02-02> patch level 5)
L3 programming layer <2020-03-06>
./chatsystem.tex:1: Undefined control sequence.
l.1 \chapter
            {メッセージングコマンドを使用した手法の提案}
? 
./chatsystem.tex:1: Emergency stop.
l.1 \chapter
            {メッセージングコマンドを使用した手法の提案}
End of file on the terminal!

 
Here is how much of TeX's memory you used:
 16 strings out of 481134
 320 string characters out of 5917333
 239393 words of memory out of 5000000
 16158 multiletter control sequences out of 15000+600000
 534979 words of font info for 42 fonts, out of 8000000 for 9000
 929 hyphenation exceptions out of 8191
 13i,0n,15p,119b,10s stack positions out of 5000i,500n,10000p,200000b,80000s
No pages of output.