I attempted the fix that was suggested but unfortunately it did not solve my problem.

I used this script:

use msdb

go

-- Backup the Agent certificate from the remote server to a file

BACKUP CERTIFICATE [##MS_AgentSigningCertificate##] TO FILE = '\\server\Shared\Backups\MS_AgentSigningCertificate.cer'

go

use master

go

-- re-create the agent certificate on master

-- Note: Because we are making these changes using a regular user and not as part of setup, the name

-- cannot include the ## token.

-- Creating a regular certificate in this case should be the equivalent as we only need it to derive a SID

CREATE CERTIFICATE [MS_AgentSigningCertificate] FROM FILE = '\\server\Shared\Backups\MS_AgentSigningCertificate.cer'

go

-- Recreate the user mapped to the cert and grant the same permissions that the regular certificate needs.

CREATE USER [MS_AgentSigningCertificate] FROM CERTIFICATE [MS_AgentSigningCertificate]

go

GRANT EXECUTE TO [MS_AgentSigningCertificate]

go

What I am failing to understand is how I would get the SQL Agent to use the [MS_AgentSigningCertificate] user instead of the still available [##MS_AgentSigningCertificate##] user.