Impersonation with SYSTEM account not work after Migration from V8.2 to V9.0--Javascript

Hi there,

I have a javascrit for create a record with Impersonation with SYSTEM account. the code works in V82 environment. but after we migrated to V90, it doesn't work anymore.

the code looks lke this:

still not work.

If I changed systemUid to any other ID of user with System Administrator, it works.

I wonder what happend in migration and what results in SYSTEM account cannot impersonate anymore.

Thanks