Database Shrink task fails
As Shanky already commented, running scheduled shrinks is wrong. There is ton of info online about it. Find the root cause of that growth and solve it. I would get rid of it immediately.

As for the error, seems related to db ownership. If you run a search with the error text your will find several related questions here, here and more.

As a recommendation, I would suggest switching to Ola Hallengren maintenance solution for administrative tasks as DBCC, index maintenance, backups, etc.