I was trying to get sync up and running between multiple FF versions I kept getting a message saying:
sync encountered an error while syncing: Unknown error.
Sync has logs in about:sync-log
I was seeing this:
Crypto check failed: [Exception... "PK11_GenrateRandom failed" nsresult: "0x80004005 (NS_ERROR_FAILURE)" location: "JS frame :: resource://gre/modules/services-crypto/WeaveCrypto.js :: WeaveCrypto.prototype.generateRandomBytes :: line 550" data: no]
Looking for a fix I found comment 33 in bug 1034979
|brew uninstall nss| and restart Fx seems to fix the problem for me.
And sure enough removing the brew installed nss package did the trick.