Hi, I use the UMAT subroutine to execute an advanced constitutive model in Abaqus 2021. However, after running a few of the many increments, I receive the following error message:

---------- RUNTIME EXCEPTION HAS OCCURED ----------

standard.exe / rank 0 / thread 3 encountered a system exception 0xC0000005 (EXCEPTION_ACCESS_VIOLATION) NUL

I also noticed that this error is not consistent. i.e. it does not show for some cases of number of increments. I checked my UMAT and could not find any bugs. I use parallel computing on a 16-core PC. I hope someone can help me with this. Please message me if you need further information.

Thank you in advance.