Apparently, I discovered that if the Canada Training Credit Limit is not mentioned on your previous notice of assessment, you will get this error #561 and it will be rejected by CRA. Therefore, I tried again after checking my 2019 NOA and without claiming the $250 training credit and it went through successfully this time.
So, check your 2019 NOA if the training credit is there. If it's not there you will not be able to claim it and it will be rejected with error message 561.
Regards,
