An unexpected error has occurred while updating diablo 3
Please check this link for more information: the Beta, several startup issues were resolved by setting the Diablo III tools to run in Compatibility Mode.At this time, Compatibility Mode for the retail tools is no longer needed.This solution I found in the forums worked for me, maybe it will work for you too…Firstly – I don’t want to take credit for this, you can find the original forum post by clicking HERE. I cannot be held responsible if something goes wrong.(to restore in case something goes wrong) Now, if the issue was the launcher not patching the Diablo III client because it was using a different patch_url, your client should be patched and you should be good to go.However, if you play in a region that’s behind your client’s version, you need to revert your client to the previous version.If it's asking for a disk then it means an entire data tome is missing from the download.
This can often times be caused by closing the downloader early.
ATI Radeon HD 4600, 4700, 4800, 5000, 60 series products are unaffected, as is Windows XP.
Update: ATI has released a Catalyst 12.4a driver hotfix for the affected cards.
Basically, the “new patch” message means your Diablo or dll does not match the version accepted by the server.
If different regions are at different versions, you need to set your patch_url to get updates meant for the region you play in.Though the downloader may show 100%, please allow some time for it to fully complete.