Apple recently released an update of Mountain Lion version 10.8.1 with fixes for Migration Assistant and iMessage. Apple on this page lists the fixes included in the upgrade.
Mountain Lion update version 10.8.1 includes the following fixes:
- Resolve an issue that may cause Migration Assistant to unexpectedly quit
- Improve compatibility when connecting to a Microsoft Exchange server in Mail
- Address an issue playing audio through a Thunderbolt display
- Resolve an issue that could prevent iMessages from being sent
- Address an issue that could cause the system to become unresponsive when using Pinyin input
- Resolve an issue when connecting to SMB servers with long names
- Address a issue that may prevent Safari from launching when using a Proxy Automatic Configuration (PAC) file
- Improve 802.1X authentication with Active Directory credentials.
Download the official update here: Download
The update has a file size of 24.2 MB and requirese OS X Mountain Lion version 10.8.