java.lang.AssertionError: Cache C:\Users\michael\.netbeans\dev\var\cache\catalogcache\net_java_dev_thinnb_update_center exists.
   at org.netbeans.modules.autoupdate.updateprovider.AutoupdateCatalogCache.writeCatalogToCache(AutoupdateCatalogCache.java:113)
   at org.netbeans.modules.autoupdate.updateprovider.AutoupdateCatalogProvider.refresh(AutoupdateCatalogProvider.java:129)
   at org.netbeans.modules.autoupdate.services.UpdateUnitProviderImpl.refresh(UpdateUnitProviderImpl.java:156)
   at org.netbeans.api.autoupdate.UpdateUnitProvider.refresh(UpdateUnitProvider.java:161)
   at org.netbeans.modules.autoupdate.ui.actions.AutoupdateCheckScheduler$4.run(AutoupdateCheckScheduler.java:147)
Caused: org.openide.util.RequestProcessor$SlowItem: task failed due to: java.lang.AssertionError: Cache C:\Users\michael\.netbeans\dev\var\cache\catalogcache\net_java_dev_thinnb_update_center exists.
   at org.openide.util.RequestProcessor.post(RequestProcessor.java:425)
   at org.netbeans.modules.autoupdate.ui.actions.AutoupdateCheckScheduler.refreshUpdateCenters(AutoupdateCheckScheduler.java:336)
   at org.netbeans.modules.autoupdate.ui.actions.AutoupdateCheckScheduler.scheduleRefreshProviders(AutoupdateCheckScheduler.java:127)
   at org.netbeans.modules.autoupdate.ui.actions.AutoupdateCheckScheduler.access$500(AutoupdateCheckScheduler.java:93)
   at org.netbeans.modules.autoupdate.ui.actions.AutoupdateCheckScheduler$6.run(AutoupdateCheckScheduler.java:430)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1424)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:1968)