The following error message is occurring when opening a older model file in WaterCAD or WaterGEMS CONNECT Edition Update 1:
Object reference not set to an instance of an object.Note: Be sure to provide a database format that is valid for WaterGEMS CONNECT Edition Update 1.
First, try opening the model with the 32-bit version of the program. You can access this by going to C:\Program Files (x86)\Bentley\WaterGEMS\WaterGEMS.exe (for file path will be similar for WaterCAD or HAMMER).
If this doesn't help, this issue can occur when a certain condition existing in the model database file (reference #803172) This issue has been fixed with a patch set for WaterGEMS, WaterCAD and HAMMER CONNECT Edition Update 1 and in all later versions of the products. If they are available, please download and install the latest version using the steps in the following link: Downloading OpenFlows Software.
If you cannot upgrade or if an update is not available, please contact technical support for more information.