Exception occurred when read Factory Serial Number from OTP


I'm using BF706 for my project. I was able to read the Factory Serial Number from the OTP memory using the function below:

adi_rom_otpadiget(otpadicmd_fsn, data);

However, after I locked the processor, I'm getting the error below when using the function above.

A non-recoverable error or exception has occurred.
Description: Attempted to use a Supervisor register or instruction from User mode (Exception with EXCAUSE=0x2E).
General Type: UnhandledException
Specific Type: SupervisorResource
Error PC: 0x04003ad2

May I know:

1) Is there any restrictions on querying the OTP memory data after processor is locked?

2) How I get rid of this?