Error: 430407803 User name not set

Hi.
I downloaded firefox on my macbook just because it seems I cannot use zotero with safari. Then I added zotero. I started to add some books and articles to My Library.

Today I set up my username and password because I wanted to sync, and now I can login but I cannot sync. I push the bottom 'Sync with Zotero Server' and then 'Open Sync preferences' but nothing appear. So I try to do the same in Action, Preferences but... nothing happen. There is just a red signal which says: User name not set.
Any suggestion?
Thanks
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