Thank you for your reply.
The PC name consists only of alphabets. There are no spaces. 
I have always built Android on Windows 11, and the last build was successful in November last year.
I am cautiously guessing that the problem occurred after applying the Appodeal 3.4 plugin in the post below.
I have also tried deleting and reinstalling the solar2d simulator,
and deleting the temporary folder,
but I don’t know how to solve it. 
As a temporary measure, I am building Android on my sub MacBook, but it is inconvenient because my main PC is Windows. 