[NotHM]

Got handed down a project from another engineer who left recently. Finally got round to giving attention to it. It compiled successfully but got that runtime error. StackTrace attached. Strange thing is the 

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Locating source for 'd:\Projects\workspace\company\Nexgen\Source\NextGen\Main\CO.Phoenix\Source\Resource\ZoomPanel\ZoomPanelMiniMap.cs'. Checksum: MD5 {64 ff 3b 9b 1d a9 ac fb 1a 96 29 31 be d8 c7 41}
The file 'd:\Projects\workspace\company\Nexgen\Source\NextGen\Main\CO.Phoenix\Source\Resource\ZoomPanel\ZoomPanelMiniMap.cs' does not exist.
Looking in script documents for 'd:\Projects\workspace\company\Nexgen\Source\NextGen\Main\CO.Phoenix\Source\Resource\ZoomPanel\ZoomPanelMiniMap.cs'...
Looking in the Edit-and-Continue directory 'C:\*REAL_LOCAL_PATH*\enc_temp_folder\'...
The file with the matching checksum was not found in the Edit-and-Continue directory.
Looking in the projects for 'd:\Projects\workspace\company\Nexgen\Source\NextGen\Main\CO.Phoenix\Source\Resource\ZoomPanel\ZoomPanelMiniMap.cs'.
The file was not found in a project.
Searching for documents embedded in the symbol file.
An embedded document was not found.
The debug source files settings for the active solution indicate that the debugger will not ask the user to find the file: d:\Projects\workspace\company\Nexgen\Source\NextGen\Main\CO.Phoenix\Source\Resource\ZoomPanel\ZoomPanelMiniMap.cs.
The debugger could not locate the source file 'd:\Projects\workspace\company\Nexgen\Source\NextGen\Main\CO.Phoenix\Source\Resource\ZoomPanel\ZoomPanelMiniMap.cs'.
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The project compiled and ran successfully at least until last week. Code hasn't been changed since. Only thing that changed in the environment is the repository link.

Can anyone give an insight to why this is happening?

[abenedik]

The file 'd:\...\ZoomPanel\ZoomPanelMiniMap.cs' does not exist.


It looks like you have purchase the full source code of ZoomPanel and that a file is missing from your local source. Please extract the source code from an official zip file again and add the missing file to your local source code folder.

[NotHM]

Thanks for the reply abenedik. I did some tracing and found the culprit.

In case I'm reading this again in the future:
* The library I'm making with this can be run in two environment
 - a development env
 - and the final prod env where it is part of a package of assemblies that installs new UI modules
* The prod env can be set up for different access levels, which requires some XAML and class code.
* The dev env to run the library cannot parse that particular XAML code piece, hence the NullReferenceException error.

Anyhoo, thanks for forcing me to do the tracing. And to my future self, don't panic.