A month ago, I created a course with a Japanese title (i.e., it began and ended with Japanese characters, although it contained one Roman letter and an Arabic numeral).
2 days ago, I attempted to modify the description (not the title) but got the Error 500 “Something has gone wrong” page when I tried to save the changes.
I tried changing the language of the category to “for Japanese speakers,” but the error still appeared. I also tried saving it in a different browser (Chrome vs. Firefox on Windows 10) to no effect.
Only after changing the title to begin with a Roman letter could I save my changes to the course.
In other words, if I want to modify and save the course details, the title can contain Japanese characters, but it cannot begin with them.