Hi,
In the source code, this assertion is probably due to the fact you have too many characters in your filename or the filename contains illegal characters, not of the ANSI type. Could graphics characters get in your filenames?
It is best to stick with ANSI CHARACTERS, not WIDE CHARACTERS as UE5 imposes stricter control on unterminated names ALL filenames must have the following terminator, where Out is the string of ANSI characters
Out[Header.Len] = ‘\0’
/// Either ANSICHAR or WIDECHAR, depending on whether the platform supports wide characters or the requirements of the licensee.
Quite a few 4.27 projects don’t convert well to 5.1, 4.26 projects convert better.
Is there a possibility that you could try converting from the 4.26 project to 5.0 EA2 perhaps