record being added contains a NULL key (message,add.schedule) error while login to Service Manager

Hi all,

While trying to login Service Manager suddenly error started coming "The record being added contains a NULL key (message,add.schedule)" and not able to login successfully.

Not sure why it started coming up suddenly and i have tried to switch the db to different instance, it was fine for a while and again the issue started with same error. I have attached the screenshot, please can any one help me what is the issue here .

If need, please let me know i will be able to share the log file.

Regards,

D_M_K