When attempting to open the WaterCAD for AutoCAD 2019 shortcut, the menus do not load in AutoCAD and the following error appears at the bottom of the command line:
Unknown command "WTRCRUN" ....
This issue is specific to WaterCAD and AutoCAD 2019 and is a known issue related to incorrect entries in the integration (note StormCAD mentioned in the command line). Reference # 890018
There are two solutions. First, you could upgrade your AutoCAD to a later, supported version, or use WaterGEMS instead of WaterCAD (if available). See: Platform Compatibility Or, use the Standalone version. See: CAD Functionality in Standalone as an Alternative to AutoCAD or MicroStation Integration
If that is not possible, try the following steps:
1) Ensure WaterCAD and AutoCAD are closed
2) Download the following file and save it to the "x64" subfolder within the WaterCAD installation folder and choose to overwrite the previous file (sign in and click the Download button): https://communities.bentley.com/products/hydraulics___hydrology/m/hydraulics_and_hydrology_gallery/275738
3) Open Registry Editor (Windows key+R, type "regedit", press enter) and delete the following registry location (the whole "STMC" folder) \HKEY_LOCAL_MACHINE\SOFTWARE\Autodesk\AutoCAD\R23.0\ACAD-2001:409\Applications\STMC
Note:- You will need elevated permissions to modify the registry. Care must be taken when doing this. Consider backing up first.- The "ACAD-2001:409" folder might be a slightly different name if you do not have the "Vanilla" version of AutoCAD (for example Civil 3D).
4) Re-run the "Integrate WaterCAD with AutoCAD..." shortcut from your Start menu.
5) Re-open the new "WaterCAD for AutoCAD 2019" shortcut.