Toad 12.9 for Oracle - Not working

I have configured Toad for Oracle to connect the Database. We are running Toad version 12.9(64bit) and Oracle Client 19c. We got an error "Access violation at address 0000000006C3E24F in module 'Toad.exe'. Read of address 00000000000000B4" Has anyone met this error before? Could you advise?

Unfortunately, that's not enough info for me to know what happened.

What did you do immediately before the error? A screen shot may help us determine what Toad is doing.

Is this the first time the error appeared? Does Toad work with other databases?

See also my comments here about getting a full error log.

If Toad has been working for a while but is now suddenly giving this error, you may need to reset your settings. There are steps to do that here.