# The following issues have been fixed
* SketchUp can crash when using Ruby plugins that call Ruby observers. In this release we addressed many of our top crashes, which should significantly improve the stability of SketchUp. The crashes were related to Ruby Observers. In particular:
- Windows > SketchUp was not correctly cleaning up observers on exit, which could lead to crashes.
- Mac > There were several issues with how observers interacted with the Mac’s multiple document interface.
* Previously, when working in SketchUp with a large number of Ruby plugins, some SketchUp context menu items could incorrectly become grayed out. With this release, this issue should happen far less frequently, if ever.
* Models created in localized versions of SketchUp 7.0 and 7.1 had a Layer0 which was translated. If those models were opened in any version of SketchUp prior to M3 and the translated Layer0 was purged or deleted, SketchUp could crash. When opening these models in Maintenance 3, the translated name of “Layer0” is no longer translated, which prevents the crash. When the model is saved, the problem is fixed for all versions of SketchUp.
* Improved messaging and workflow for users without a nickname: In order to use the 3D warehouse, users must login using a Google account that has a nickname associated with it. Previously, when logging into the 3D warehouse using an account with no nickname, the login would fail. In this version, users without a nickname now see a better error message and are directed to a login screen to add a nickname.
* Mac: Previously, when using the Ruby method Entities.add_group(), performance was much slower than on Windows. This issue has been fixed.
# New functionality
* SketchUp now only uses one network license seat when launching multiple instances of SketchUp on the same Windows machine. Previously, when using a Windows network license each instance of SketchUp would use a separate license seat. In this version, launching multiple instances of SketchUp on the same machine will now result in only one network seat being used.
* More secure image libraries, better protected from potential security vulnerabilities.
* Added a link displaying Open Source Credits in the About Google SketchUp dialog.
* Mac: We made a change that made uploads to the 3D Warehouse more reliable.