Revit could not complete the external command... Missing file

Runtime Error 5 running FDT command on Metric drawing

Blacked out cells in Head Selector dialog

After clicking the Start AutoCALCs (SAL command) button but BEFORE the AutoCALC Setup window, you get the error; 

Unhandled exception has occurred in a component in your application. If you click Continue, the application will ignore this error and attempt to continue.

The input string '1◆' was not in a correct format.

 No inch marks (“) after the pipe diameter or there are but you prefer to remove them

After opening AutoCAD and a drawing, you have a dead area where you can't draw nor does anything display.  Usually next to a compressed palette.  Note in the image below how the crosshairs do not extend to this area.

Yellow part numbers that do not list

When saving the file, no hvuf file gets created, and run-time error 3021 appears

 Line / Main tags are blocking items behind the text / tags are not transparent

Revit could not complete the external command... Revit encountered a Attempt to modify the model outside of transaction...

Pop-up immediately after selecting RTS Points

The location that your document is saved in cannot be used. Please select that folder that you would like RTS data saved to,

Command Failure for External Command... Object reference not set to an instance of an object

Calc process gets stuck on step 5a.3b
This is caused bad pump routing.

System.IO.DirectoryNotFoundException: Could not find a part of the path

Cannot get HydraLIST to print out pipe sketches with 1/8" units

Dup Equiv K / Sys Pipe Node

Edit Remote Area dialog box is cut off (Can also happen to the main HydraCALC for Revit Setup dialog box)

Hydraulic Calculations runs, the Calc Process finishes, but no nodes are placed and a HydraCALC file isn’t created.

Can also hang as step 2.3, depending on program version. 

When trying to insert a Sprinkler Head Schedule (SHS command), after viewing the setup dialog box, then selecting sprinkler heads, when asked to select a location for the guide, you get the error;

Please pick start point for schedule

Error: bad argument value: non-negative: -1