UnboundLocalError: local variable 'fdst' referenced before assignment

Hi

I need your help again. Thanks

I got the below error time to time, I have no idea what was wrong. If I reboot my pc, then the error goes away. Sometime I have to wait to reboot pc later. Do you guys have this error before? Thanks

Abaqus 2020HF5
UnboundLocalError: local variable 'fdst' referenced before assignment