In the past I had already implemented successfully automatic migration from version 1 of my data model to version 2. Now, using SDK 3.1.3, migrating from version 2 to version 3 fails with the following error:

Unresolved error Error Domain=NSCocoaErrorDomain Code=134110 UserInfo=0x5363360 "Operation could not be completed. (Cocoa error 134110.)", { NSUnderlyingError = Error Domain=NSCocoaErrorDomain Code=256 UserInfo=0x53622b0 "Operation could not be completed. (Cocoa error 256.)"; reason = "Failed to save new store after first pass of migration."; }

I have tried automatic migration using NSMigratePersistentStoresAutomaticallyOption and NSInferMappingModelAutomaticallyOption and also migration using only NSMigratePersistentStoresAutomaticallyOption, providing a mapping model from v2 to v3.

I see the above error logged, and no object is available in the application. However, if I quit the application and reopen it, everything is in place and working.

The Core Data methods I am using are the following ones

- (NSManagedObjectModel *)managedObjectModel {

    if (managedObjectModel != nil) {
        return managedObjectModel;
    }



    NSString *path = [[NSBundle mainBundle] pathForResource:@"MYAPP" ofType:@"momd"];
    NSURL *momURL = [NSURL fileURLWithPath:path];
    managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:momURL];

    return managedObjectModel;

}
- (NSManagedObjectContext *) managedObjectContext {

    if (managedObjectContext != nil) {
        return managedObjectContext;
    }


    NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator];
    if (coordinator != nil) {
        managedObjectContext = [[NSManagedObjectContext alloc] init];
        [managedObjectContext setPersistentStoreCoordinator: coordinator];
    }
    return managedObjectContext;
}



- (NSPersistentStoreCoordinator *)persistentStoreCoordinator {

    if (persistentStoreCoordinator != nil) {
        return persistentStoreCoordinator;
    }


    NSURL *storeUrl = [NSURL fileURLWithPath: [[self applicationDocumentsDirectory] stringByAppendingPathComponent: @"MYAPP.sqlite"]];


  NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
  [NSNumber numberWithBool:YES], NSMigratePersistentStoresAutomaticallyOption,
  [NSNumber numberWithBool:YES], NSInferMappingModelAutomaticallyOption, nil];

  NSError *error = nil;
  persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel: [self managedObjectModel]];
   if (![persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeUrl options:options error:&error]) {
        // Handle error
        NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
   }  


return persistentStoreCoordinator;

}

In the simulator, I see that this generates a MYAPP~.sqlite files and a MYAPP.sqlite file. I tried to remove the MYAPP~.sqlite file, but

BOOL oldExists = [[NSFileManager defaultManager] fileExistsAtPath: [[self applicationDocumentsDirectory] stringByAppendingPathComponent: @"MYAPP~.sqlite"]];

always returns NO. Any clue? Am I doing something wrong? Thank you in advance.