exception of type 'Autodesk.Revit.Exceptions.InvalidOperationException'

[62BJW]

I'm attempting to change all "Swing Angle" parameter for all the doors in the project. I'm getting the following error in the foreach loop. No elements are being deleted as the error describes.

An exception of type 'Autodesk.Revit.Exceptions.InvalidOperationException' occurred in RevitAPI.dll but was not handled in user code

Additional information: The iterator cannot proceed due to changes made to the Element table in Revit's database (typically, This can be the result of an Element deletion).

Here is the code.

Thanks.

            FilteredElementCollector coll = new FilteredElementCollector(doc)
            .OfCategory(BuiltInCategory.OST_Doors)
            .OfClass(typeof(FamilyInstance));

            // Filtered element collector is iterable

            foreach (Element e in coll)
            {
                // Get the parameter name
                Parameter parameter = e.LookupParameter("Swing Angle");
                using (Transaction t = new Transaction(doc, "parameters"))

                // Modify document within a transaction
                using (Transaction tx = new Transaction(doc))
                {
                    tx.Start("Transaction Name");
                    try
                    {
                        parameter.Set(0.785398163);
                    }
                    catch { }
                    tx.Commit();
                }
            }

[so-chong · Accepted solution]

Hi,

 To avoid this kind of error, maybe you could try something like this

    FilteredElementCollector collector = new FilteredElementCollector(doc);
     List<Element> coll = collector.OfClass(typeof(FamilyInstance))
         .OfCategory(BuiltInCategory.OST_Doors)
         .ToList();
     
     // Filtered element collector is iterable
     
     foreach (Element e in coll)
     {
     
         // Get the parameter name
         Parameter parameter = e.LookupParameter("Swing Angle");
         using (Transaction t = new Transaction(doc, "parameters"))
     
         // Modify document within a transaction
         using (Transaction tx = new Transaction(doc))
         {
             tx.Start("Transaction Name");
             try
             {
                 parameter.Set(0.785398163);
             }
             catch { }
             tx.Commit();
         }
     }

Hope this helps.

[62BJW]

Perfect. Thanks!

[jweber-]

Any chance you could explain why this error is occurring, and why your solution works? I tried it for my issue and it solved it, but I'm unclear as to why. I'm just wandering why you need to make a list?? Thanks in advance...

[aclarke]

I believe it is because you are trying to make the changes inside a FilteredElementCollect vs a List.

Turn your collection into a list and work with the List not the Filter Collection.

deleting-a-collection-of-elementsfamilies-the-correct-approach. 

[jweber-]

Thanks! That link is useful too, much appreciated.