Problems deploying from the moddeler

All of a sudden, on two of our development stations, Mendix throws a fit when we try to run the App from the moddeler for testing. All I get in error-messages is the one below... Caused by: java.lang.NullPointerException: null     at com.mendix.connectionbus.modelsynchronization.ModelSynchronizationUpdater.validateConstraint( Is this caused by a temporary miscommunication with the repository ?   ** updated status : the main-line of the App still runs without any hick-up from the local moddeler, but any branche I create runs into the situation described   Included full stacktrace....   help would be appriciated, this is criplings us at the moment.... An error occurred while initializing the Runtime: null -------- com.mendix.m2ee.api.AdminException: An error occurred while initializing the Runtime: null at com.mendix.basis.impl.MxRuntimeImpl.start( Caused by: java.lang.NullPointerException: null at com.mendix.connectionbus.modelsynchronization.ModelSynchronizationUpdater.validateConstraint( at$3$1.accept( at$ForEachOp$OfRef.accept( at$3$1.accept( at java.util.HashMap$ValueSpliterator.forEachRemaining( at at at$ForEachOp.evaluateSequential( at$ForEachOp$OfRef.evaluateSequential( at at at$7$1.accept( at$2$1.accept( at java.util.ArrayList$ArrayListSpliterator.forEachRemaining( at at at$ReduceOp.evaluateSequential( at at at com.mendix.connectionbus.modelsynchronization.ModelSynchronizationUpdater.analyzeConstraints( at com.mendix.connectionbus.modelsynchronization.ModelSynchronizationUpdater.validateConstraints( at com.mendix.connectionbus.modelsynchronization.ModelSynchronizationUpdater.analyzeAndRender( at com.mendix.connectionbus.modelsynchronization.SynchronizationManager.analyzeModel(SynchronizationManager.scala:176) at com.mendix.connectionbus.modelsynchronization.SynchronizationManager.analyzeCurrentDatabase(SynchronizationManager.scala:98) at com.mendix.connectionbus.modelsynchronization.SynchronizationManager.analyze(SynchronizationManager.scala:87) at com.mendix.connectionbus.ConnectionBusImpl.collectDatabaseSynchronizationInformation( at com.mendix.basis.impl.MxRuntimeImpl.initializeConnectionBusAnyway( at com.mendix.basis.impl.MxRuntimeImpl.start( at com.mendix.basis.impl.MxRuntimeImpl.start( at com.mendix.m2ee.appcontainer.actions.StartAction.startRuntime( at com.mendix.m2ee.appcontainer.actions.StartAction.execute( at com.mendix.m2ee.appcontainer.server.handler.HttpAdminHandler.handle( at org.eclipse.jetty.server.handler.HandlerWrapper.handle( at org.eclipse.jetty.server.Server.handle( at org.eclipse.jetty.server.AbstractHttpConnection.handleRequest( at org.eclipse.jetty.server.AbstractHttpConnection.headerComplete( at org.eclipse.jetty.server.AbstractHttpConnection$RequestHandler.headerComplete( at org.eclipse.jetty.http.HttpParser.parseNext( at org.eclipse.jetty.http.HttpParser.parseAvailable( at org.eclipse.jetty.server.AsyncHttpConnection.handle( at at$ at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob( at org.eclipse.jetty.util.thread.QueuedThreadPool$ at  
1 answers

Working with Jaap @ Mendix support we used a work-around going to Modeler version 7.9

This because a similar stacktrace issue was fixed in that version 

We fixed the issue where creating a new attribute for an entity and a unique constraint on that same attribute at the same time made the synchronization fail. (Ticket 58516)

I am 100% sure that we did not add unique constraints, but we did revise the Domain Model significantly.

Still does not explain why I even get the same issue when "loading" the unaltered mainline on a werkstation previously not used for this App........

### update ###

To work around this bug, you can temporarily disable Unique constraints in the database, see Project Settings, tab Runtime, at the bottom: Uniqueness validation. Set this temporarily on Runtime, start your app, and do the necessary database synchronization actions. After being started correctly, set this setting again to Database. Restart and everything should work.

and that did the trick in 7.5.1...........     

that, and making sure that there are no duplicate port-settings on two branches of the same App on your computer...........