Problem

When computing a model, one of the following error messages is generated:

"Calculation cancelled by user"

"Specified cast is not valid"

"System.ArgumentException: An item with the same key has already been added."

Solutions

Solution 1

This issue can occur when there is a catchment where the property field for, "Use local rainfall?" is set to True, but no storm is selected. To resolve this, either assign a storm as the local storm for the catchment or set "Use local rainfall?" to 'False'.

If you have multiple scenarios that use different 'Rainfall Runoff' alternatives make sure you uncheck the checkbox for all the catchments that have "Use local rainfall?" checked. The alternatives can be accessed by going to (Analysis > Alternatives) and double clicking to access the properties.

Solution 2

Catch basins cannot have multiple downstream gutters. This warning dialog will appear if the model contains this and is using the Explicit (SWMM) solver

See Also

Error importing InRoads file: "Item has already been added. Key in dictionary: 'DUMMY INLET' Key being added: 'DUMMY INLET'"

Error in ModelBuilder: <Element Type> Error: Unable to open table. An item with the same key has already been added