Unable to select a pipe or fitting when trying to use the Delete Pipe tool.

TWO SYMPTOMS:

Drawing fittings and pipe look disjointed, like that time an alien team of scientists were performing out-of-phase medical experiments on the Voyager crew.

Or, on the way into Revit, you get this error;

Error (must be addressed in order to continue)

Revit has experienced an unexpected error.  The operation has been cancelled to protect your project from corruption

Deleted element

When reporting the error, you may see this;

Hashtable head_table, Hashtable FLXpipeTable, List '1 listFtgs, flexpipes PipeTypeInfo ptInfo

When inserting a vertical pipe/riser nipple with a fraction in the diameter you get atypical results

The fonts for fraction symbols ¼ (quarter), ½ (half), or ¾ (three-quarters) are replaced with ?.840, ?1.050, and ?1.660

When printing a final calculation, the font doesn't show fraction symbols for ¼ (quarter), ½ (half), or ¾ (three-quarters)

They're replaced with ?.840, ?1.050, and ?1.660

These should look like this;

Of note, if using HydraCAD for AutoCAD, you get similar results on riser nipples/vertical pipes 

When you insert your vertical pipe/riser nipple, you see the text "HCAD/D_UNITS" as the diameter's suffix

When starting AutoCALC, it stops in the v50 Fuel Gauge at step 1a.4 - Calculating Total Lengths. 

Working on the pipe from node #### to node #### with a fitting string of ...

May be followed by a Runtime Error 13 or Runtime Error 5

Your first step of troubleshooting should be to track down the coordinates of the handles (the 4 to 6 character hex code noted after the word node, or pipe, or fitting.  Search for the command FINDME to get these coordinates.

When starting AutoCALC the v50 Fuel Gauge stops at step 1a.4 plus you get a Run-time error 6; Overflow 

Working on pipe from Node ### to Node ### with a fitting of "?" and a diameter of / pipe type of 0.5 / SCHED-40 where the pipe id = ### 

The "####" values represent handles.  It is recommended you use the FINDME tool to find the coordinates of the handles, this will help narrow down the cause of the error.

May also see a Runtime Error 5, "invalid procedure"

When attempting to insert a pipe dimension you get the error "Invalid option keyword"

And the command prompt says "Enter an UNDO control option" with the dialog showing your choices

When starting the Pretty Pipes command, you get an Unhandled Exception error including 'Could not find a part of the path'

Another error may mention blockoffsets.dat

When attempting to create a 3D model, you get the error; Please switch to System Model to Annotate Drops and Sprigs plus

System.NullReferenceException: Object reference not set to an instance of an object

at HCADexports.RevitConversion.create_hydrapipes_from_db()

at HCADexports.RevitConversion.create_hydrafittings_from_db(List'1 pipes, List'1 heads)

Setting certain pipe diameters with specific pipe types gives an ID of 0.

Eg. 1½" - SCHED 40 shows up as 0 rather than 1.61. n/a HydraCalc

The font of your vertical pipes do not match the font of your pipe dimensions

Calc process gets stuck on step 5a.3b

All layers where objects should appear white in AutoCAD will randomly turn brown in color (colors 18, 19, 248, or 249)

Note the pipe dimension and main piping in the image above are brown instead of white.

When inserting a listing tag on a pipe, you get the error, "Invalid color number"

Double-Clicking on a riser nipple, or using the Edit Riser Nipple command (ERN) briefly displays the edit riser nipple dialog, which then closes

After attempting to download the Latest Toolbox, a warning appears saying the file cannot be opened. 
Tells user to delete toolbox .rvt file and try again, but that does not work. 

When attempting to insert a cap, it draws the pipe and dimensions it, but it doesn't insert a cap.

However if you draw a test pipe elsewhere, it successfully inserts the cap for you

When running the "FSC Setup" to "Create FSC Definition". 
Upon finishing the block definition, the block definition is missing a crucial property for "Hydraulic equivalent length is referenced by:". This field will show blank or the default generic text and did not include the HydraCALC pipe/fitting reference information.

There is a missing HydraCALC "ImportExport" directory.

Default line text:
`Hydraulic equivalent length is referenced by: shortname with length number - longname Listing: FM`

When selecting a pipe for the Move Main command, you get a fatal error