I haven't seen this error before, but if I were to troubleshoot the issue I would download a mod, extract the files, open the .gr2 with NexusBuddy and try to view it. If that fails then you have a problem with either .NET, the paths where you installed Nexus and/or NexusBuddy, or a corrupt file. If it succeeds then I would recommend downloading a worker.gr2 model that does not originate from your source Civ files (assuming that is where you got the worker.gr2 file) and using that as your base model instead.
EDIT: Additionally, I actually recommend .NET 4 or greater, and make sure that your NexusBuddy .config file looks like this:
Code:
<?xml version="1.0"?>
<configuration>
<startup useLegacyV2RuntimeActivationPolicy="true">
<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0"/>
</startup>
<runtime>
<loadFromRemoteSources
enabled="true"/>
</runtime>
</configuration>
To avoid any future pitfalls, make sure your registry entries point to the correct location per the tutorials:
Code:
[HKEY_CURRENT_USER\SOFTWARE\Firaxis\Nexus\Viewer]
"Executable"="<the location where you put the OLD (working) Nexus Viewer>\\Viewer.exe"
"AssetPath"="C:\\Program Files (x86)\\Steam\\steamapps\\common\\Sid Meier's Civilization V\\Assets" (Usually, if you use Steam; otherwise, the path to your Civ V Assets folder)