Diablo III's EU servers have apparently failed to fully recover from patch 1.0.2's delivery yesterday, with European players complaining of consistent errors 37 and 73 when trying to log-in today.
Play has been sporadic since Blizzard deployed the patch, and hundreds of people are complaining of being unable to log-in today despite servers in all regions being displayed as live.
One thread on the Blizzard forums is now at over 1,000 posts, with constant complaints of error 37 and error 73 (look in "popular topics" on the right), which respectively say servers are too busy and that Battle.net is offline.
The latest update warns users that although "the service" is back online, error 37 will continue while loads are high.
"The authentication process can take up to 30-40 seconds. Please wait for this process to complete instead of cancelling and restarting the login," Blizzard requested.
The publisher assured fans earlier that: “We’re aware that many players are receiving error 37 when logging into the game. Please note that this error indicates that all servers are full, and that we’re currently receiving a high volume of log-in traffic.
"We’re working to reduce the frequency at which players are prompted with this error message and ensure that everyone can successfully log in to the game and play."
Blizzard has come under fire from fans over server issues since launching Diablo III on May 15, especially in the first 48 hours after release.
Diablo III requires a constant internet connection to play.