Many fans who use the Mac app Store to update/download software may have been plagued by "unknown errors" and how to solve them. However, after a period of time do not know what to do and their own good. Today we offer two ways to solve this problem and you can try it the next time you encounter this problem.
1, first confirm that the Mac app Store and ITunes are logged in with the same Apple ID account. Some fans may have two or more Apple IDs, such as family and friends, such as a Chinese account, a U.S. account, and so on. If ITunes and Mac app Store are not logged on to the same Apple ID, then there is a good chance of an "unknown error" problem.
2. After logging in with the same account, exit the Mac app Store and itunes (if itunes is running).
3, rerun the Mac app Store, many times can be solved.
If it still doesn't work out, it could be that Apple has updated iTunes terms of use and you haven't agreed to the new terms. If this is the reason to solve it is also very simple:
1, run ITunes (if it is running state, then quit and then restart);
2, accept the new iTunes terms of use;
3, restart the Mac app Store.
