When trying to install HydraCAD, you get an error;

HydraCAD Version 58 must be installed on this computer before running this update.  Please download and install the full install of v58.

When hitting Save, Refresh Drawing or Calculate Results, user gets a Run-time 9 error. AKA Subscript out of Range

When opening AutoCAD, you get an error saying "a software problem has AutoCAD to close unexpectedly"

Upon reviewing the file it's crashed on, it shows HCAD_MAKEFIGHANGERLIST as the culprit

Revit could not complete the external command... Curve length is too small for Revit's tolerance

HydraLIST completes listing process, but will not open.

Continue button is Grayed out, and I cannot proceed with my calculation.

No Ribbons / only the HydraCAD Ribbon appears, and no commands work.
Revit could not complete the external command. Could not load file or assembly. The system cannot find the specified file. 

When trying to open a calc job using [File|Open], you get a Run-time error '62': Input past end of file

When selecting Adjustable Ring Hangers for pipe sizes larger than 8" the detail does not show.

While in your viewport, your riser is visible while in the 2D Wireframe view.  However if you change the Visual Style to Conceptual or Shades of Grey/Shades of Gray, your 3D riser disappears.  You may notice if re-appears if you zoom out.

After printing your data in HydraLIST, when HydraVIEW opens you attempt to change the default printer. 

You get an error "Page Setup - Unknown filetype found 'HLTF'"

When opening HydraCALC SIZER, you get the error;  Run-time error '53': File not found

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

During the install of HydraCAD, you get an error, "Setup Needs the Next Disk, Please insert disk 1 that contains the file data2cab"

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

When closing a drawing in 3D, and later re-opening and returning to 2D, some of the drawing symbols show up looking like outlines (Hangers, Sprinklers, etc)

HydraCAD Critical Error... Visual Lisp not available

Error appears when opening Hangers

Failed to load the following families: z_Pipe Elevation Marker

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

Runtime Error 5 running FDT command on Metric drawing