unknown error when signing into iTunes

Hey abdi59,

As we understand it you're experiencing an error when attempting to sign into iTunes on your Mac.

Do you receiving any specific error code? It'll help us isolate our next steps. In the meantime, take a look through the steps in the following article that help resolve most errors you may have with the iTunes Store:

• If you can't connect to the App Store, iTunes Store, or other Apple services

If the issue persists, let us know additional details about the error you're receiving, and we'll proceed from there.

Cheers!