Sometimes when I call saveToPersistent on the RestKit MainQueueManagedObjectContext I get the following error and the app crashes. 

CoreData: error: Serious application error.  Exception was caught during Core Data change processing.  This is usually a bug within an observer of NSManagedObjectContextObjectsDidChangeNotification.  -[UIBarButtonItem controllerWillChangeContent:]: unrecognized selector sent to instance 0x21e70300 with userInfo (null)

[UIBarButtonItem controllerWillChangeContent:]: unrecognized selector sent to instance 0x21e70300 with userInfo (null)


It seems that there are some kind of threading problem. 

I save the context via a method like so: 

- (BOOL)saveMainContext
{
    __block BOOL contextSaved = NO;
    [[[[CoreDataManager sharedInstance] objectStore] mainQueueManagedObjectContext] performBlockAndWait:^{
        NSError *error = nil;
        if ([[[[CoreDataManager sharedInstance] objectStore] mainQueueManagedObjectContext] saveToPersistentStore:&amp;error]) {
            contextSaved = YES;
        }
    }];

    return contextSaved;
}


It crashes on the saveToPersistent method with EXC_BAD_ACCESS.
How can I fix this and what could be the reason for my NSFetchresultscontroller calling a method on a UIBarButtonItem? 


Question: accessing .xls file and saving in folder for ubuntu
Answer: You can copy it using cp or move it using mv. For example

find . -type f -name '*.xls' -exec cp '{}' /path/to/folder/ \;


The folder must already exist.