Gremlins in My Drawing!

“What is wrong with AutoCAD?  It takes forever to open drawings and forever to save.  My drawings have ballooned to ten times the size they were last week and doing anything in the program is so slow!  When I ask IT for help, they uninstall and reinstall AutoCAD with no improvement. When I tell them the problem isn’t resolved, they uninstall and reinstall once more with, again, no improvement. What is going on?”

I’ve heard variations of this story time after time after visiting the offices of various organizations, even recently over my last 10 years of working as a staff member for engineering firms. What surprised me is that even though the cause of this issue is an age-old problem, it isn’t a problem that has been eliminated from the industry. Using old drawing data that may come from an old block library, templates, or old drawing files is usually the source of the problem. The issue has been known about for many years. The cause of this issue would be unreferenced registered applications, gremlins in AutoCAD, that become a huge problem because they continue to exist unrecognized by some and unacknowledged by others regarding the damage they can do to drawings.

Registered applications are created when a drawing comes into contact with a third-party function. A third-party function comes from third-party software installed on top of AutoCAD. Its commands are available only inside of AutoCAD. A registered application becomes associated with an entity such as a polyline when you ask that third-party software to recognize it as an alignment, for example. This is the way that the third-party software can continue to recognize it as an alignment so it can apply station text, create roadway offsets, or produce another polyline that represents the profile over a surface. Not all third-party applications are harmful and most that are still being used today create no issues.

The registered applications that become a problem are the ones that are no longer being used. Sometimes third-party applications are dropped for others that may be better. Just because you uninstall a third-party application doesn’t mean it goes away. Its registered applications are left behind inside drawings. Even if you take a drawing and delete everything out of it, the register applications still remain. Sometimes these cleaned-up drawings are used for templates, or blocks, or external references. Through this usage, they multiply, spread, and corrupt, causing terrible performance issues and unrecoverable corruption.

At some point in time, Autodesk provided a tool for purging these things out of a drawing in the command line version of Purge; it is not available from the dialog version of Purge. You must type at the command line ‘-purge’. This will trigger a few prompts and then commence to purge all registered applications out of the drawing. The keystroke sequence is:  -purge <enter> r <enter> * <enter> n <enter>. The command line will look something like this:

The above image depicts the purge command being executed in a drawing without problems.

Here is the text window of a drawing being purged of harmful registered applications and notice the number of applications deleted:

Notice the number of applications is exorbitant.

The purged registered applications that are needed will come back when the drawing is opened again as long as the third-party software is present. And other entities previously created by the third-party software will remain. The unreferenced registered applications will not return unless they are originating from an attached external reference.

To completely remove these out of your project, there is a utility Autodesk created that can be downloaded from here. With this tool, you can select a folder full of drawings, and have the registered applications purged out of them and any attached external reference. The best time to do this is at night. If any of the drawings are open during this process, they will not be cleaned since they cannot be saved. The utility comes with installation and operation instructions, and you must be an administrator to install.

The ‘Regapp ID Cleanup Utility’ is launched outside of AutoCAD and a dialog displays.

Option 1

With Select Folders selected,

• Browse to the folder containing the drawings.
• Select the folder, click OK, and the drawings inside that folder will be listed in the dialog.
• If Include Sub-folders is checked, then all drawings in the sub-folders will also be included.
• If Include Xref Files is checked, all Xrefs will be listed. This will also set off a chain reaction.  As each file is loaded and purged, if that file has additional Xrefs attached, then those will be added to the list.  So, an initial list of thirty files can grow to three hundred files during the purge process.

Option 2

With Select Files selected,

• Browse to the file, select OK, and the file will be listed in the dialog.
• Repeat as necessary to include other files.

For affected projects, use Option 1. It is the most thorough of the two, but requires to be run overnight since it is hard to determine how many drawings will end up being purged.

Best Practices

• Do notify all Team members that they must be out of the drawing by the end of the day so the utility can run.
• Use the Task Scheduler to schedule the utility to run after hours when all team members are finished for the day.
• After the registered applications are purged, then the drawings should be audited as they are opened thereafter.
• Any drawings received from clients, consultants, or even other departments should be purged of all registered applications and audited before integrating them into the project.

Eliminating all forms of drawing corruption, including registered applications will keep your drawings healthy. AutoCAD will perform faster with no errors or crashes which will reduce the likelihood that you will be contacting IT to help you resolve issues. Any drawing files you share with clients, contractors, or consultants will not propagate drawing-related gremlins in their drawing sets. Corrupt registered applications will also interfere with the execution of commands in AutoCAD Civil 3D and as well as third-party software. So, cleaning them out of all of your projects should be an essential component of your overall CAD Management process.

 – Cyndy Davenport