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Hi everyone, I posted this over in the NI forums as well, but maybe I'll have more luck over here. I just ran into an issue this morning after building an executable version of my program, which uses the Actor Framework. It contains a .NET control (version 3.5) on one of my front panels. There's a function that I call to pass some XML strings to the control, which then handles filling in the data. This works just as expected in the development environment, but when I build an executable and run that, the control just sits there without being properly filled in. I attached an error indicator to the invoke node, which is showing me this error: Error calling method InstrumentDataGridView.InstrumentDataGridView.LabVIEW_FillTableFromXML, (System.ArgumentNullException: Key cannot be null.Parameter name: key) <append><b>System.ArgumentNullException</b> in Experiment UI.lvlib:Experiment UI Panel.lvclass:Actor Core.vi:1->Actor Framework.lvlib:Actor.lvclass:Actor.vi:4->Actor Framework.lvlib:Actor.lvclass:Actor.vi.ACBRProxyCaller.D140000E I then ran DebugView to get some more detailed information on what was happening and here's the log that it spit out: 00000006 80.98936462 [3404] Created new AppDomain: ICAS-EPR.exe for Reflection 00000007 82.80818939 [3404] Created new AppDomain: ICAS-EPR.exe for Run 00000008 85.75064087 [3404] DNError: Error calling method InstrumentDataGridView.InstrumentDataGridView.LabVIEW_NotifyAcquisitionStopped (1172). System.ArgumentNullException: Key cannot be null. 00000009 85.75064087 [3404] Parameter name: key 00000010 85.75064087 [3404] at System.Collections.Hashtable.get_Item(Object key) 00000011 85.75064087 [3404] at NationalInstruments.LabVIEW.SyncInvokeTable.LookupControl(Object key) 00000012 85.75064087 [3404] at NationalInstruments.LabVIEW.DNRuntime.InvokeMethod(Int32 invokeType, Type type, ObjectId objectId, String methodName, Type[] parameterTypes, Int32[] parameterFlags, ObjectId[]& parameterIds) 00000013 85.75064087 [3404] 00000014 114.37963104 [3404] DNError: Error calling method InstrumentDataGridView.InstrumentDataGridView.LabVIEW_FillTableFromXML (1172). System.ArgumentNullException: Key cannot be null. 00000015 114.37963104 [3404] Parameter name: key 00000016 114.37963104 [3404] at System.Collections.Hashtable.get_Item(Object key) 00000017 114.37963104 [3404] at NationalInstruments.LabVIEW.SyncInvokeTable.LookupControl(Object key) 00000018 114.37963104 [3404] at NationalInstruments.LabVIEW.DNRuntime.InvokeMethod(Int32 invokeType, Type type, ObjectId objectId, String methodName, Type[] parameterTypes, Int32[] parameterFlags, ObjectId[]& parameterIds) 00000019 114.37963104 [3404] 00000020 133.64822388 [3404] Destroying AppDomain: ICAS-EPR.exe for Reflection 00000021 133.68054199 [3404] Destroying AppDomain: ICAS-EPR.exe for Run As you can see, I get a "System.ArgumentNullException: Key cannot be null." error when calling both LabVIEW_NotifyAcquisitionStopped and LabVIEW_FillTableFromXML. Neither of these functions throw that type of exception. I thought that maybe the constructor wasn't being called, but I added some code to the constructor to write to a file and that functioned as expected. Then I wrote a new function that wrote to a file and called that when the VI loaded. That function worked fine and didn't throw any errors. I am completely stumped as to why this is happening. Both the development environment and the executable use the exact same DLL code. I appreciate any help I can get!

This took a decent amount of debugging and headscratching to figure out why a particular .NET call kept failing. I inadvertently discovered and wired a "vestigial" output terminal that exists on .NET Constructor Nodes in LabVIEW 2012. Interestingly, this output terminal returns the same datatype as the "real" output terminal, yet does not return a valid ref. Pretty sure this is a CAR-able bug, but just documenting behavior here just in case someone else runs into this. (Can you think of possibilities to exploit this as a feature??) Here's a 47sec YouTube video with no sound; Vestigial Terminal at 25sec: ...and for the sake of organic search: Error 1172 - "LabVIEW: A .NET exception occurred in an external assembly. For information about correcting this error, copy the following exception (in bold), and search the Microsoft Developer Network (MSDN) Web site or the Web for a possible explanation." And in case the resolution for this "error" and my "bug" was not clear: I just had to rewire the terminal to the "correct" output. Further, my choice of .NET assembly, constructor and property for the demonstration was arbitrary; this appears to affect all .NET Constructor Nodes.