When running an autolist, you're no longer getting the listing tag IDs such as MAIN A.1, MAIN A.2, MAIN A.3, etc show up on your drawing.  It only shows the original tag of MAIN A 

Same can be said for line tags #LN1.1, #LN1.2, etc

The diameter tag HANDLE is 0000 this number is used to determin if the pipe is sloped - yielding an incorrect pipe length. Move Line / Move Main make the diameter tag HANDLE be 0000

Revit could not complete the external command... The 3D view ownerDBViewId is not locked

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

Double-clicking your HydraCALC icon makes nothing happen.  You do not see HydraCALC open onscreen nor on your taskbar.  

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.

If you see entries here, use END TASK to get rid of them.  Scroll into BACKGROUND PROCESSES as well as they may not show up in "Apps"

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.

Printing a calc shows this error in HydraVIEW;

File not found Runtime Error 53

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

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)

3D Details (3D Fittings) missing, only the skipoles are showing

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

Calc stops at Step 2.3 (Can also show Run-time error 62)

When starting the AutoLIST process, the message box shown below pops up.  The process "pretends" to continue through, but when HydraLIST opens, it's completely blank.

After running an Autolist, in HydraLIST and the LINES tab you have a listing tag ID called RM

Upon starting the Show 3D command (S3D) the drawing immediately switches to SE isometric, reports no errors but no 3D piping is visible.  Even newly drawn pipe won't elevate.

Drawing successfully elevated to 3D. No errors were found

Related HydraCARD: #853

https://hydracards.hydratecinc.com/cards/card-853

Greyed out options in the Addin Assistant and ribbons do not appear in Revit

Primary calc results are shown, and when selecting OK to continue back to the calc input screen, the two messages below are displayed, twice;

"The designated source node was not found in the list of pipes" OK

"Calculation failed for an unknown reason" OK

Process Error Hydcalc

When selecting a vertical pipe/riser nipple hydrapipe, the PROPERTIES window shows "no selection" instead of "hydrapipe"

You may notice that you cannot use the 'change length' command (CL) or cannot rotate riser nipple (RRT)

Hydrapipe - vertical pipe issue Switching to Edit Mode leaves HydraPipes in Hydrapipe layer. Then when trying to show system model you get an AutoCAD message box "Please Switch to Edit Mode. Then try again." Switch to Edit....

Unhandled Exception... System.ArgumentOutOfRangeException: Index was out of range

No error... but the view shows up in the project browser but quickly disappears after and cannot be accessed.