When viewing a plot, hydraulic reference points in the HYD2 layer have thick text.  Editing lineweights for the layer does not make a difference.

Double-clicking your HydraCALC icon makes nothing happen.  You do not see HydraCALC open onscreen nor on your taskbar.  HydraCALC does not open other than in the task manager.

If you open your task manager and see the app "Hyd_prog.exe" open but not on your taskbar, then the application is stuck in purgatory.

Another possibility may be that it's on the taskbar but not on your screen.  That means it's open but offscreen. 

See this HydraCARD to fix that issue;  HydraCARD 565 only AFTER you've checked on the solution below.

Error occurs when tying to select any option in the Hangers button

Using negative floor elevations and drop windows with specified lengths, drops give a warning that takeout was greater than it's length, when going to 3D.

After starting the AutoLIST process, you get an error saying, "Error with Drop/Sprig annotation...  This one will be displayed"

After clicking OK, HydraLIST opens but you won't see any cut lengths of your sprigs and drops in the layer DropSprigTextCL

File name asked for does NOT exist

FitExch.dat 1.a.1

Error Finding Hanger Information when generating 3D Hangers

Create 3D Hangers command did not created 3D hangers for the #01B hanger assembly but it did for all other hanger assembly types. #01B 3D hanger information is not in the DAT file. HydraCAD v50

Revit could not complete the external command... Family symbol is not valid for this instance

When running a calculation, the value for "pressure required" shows a negative value.