Overview of DXF and DWG File Formats

DXF (Drawing Exchange Format) and DWG (Drawing) are two popular file formats used for storing 2D and 3D design data. They are widely used in CAD (Computer-Aided Design) software for exchanging drawings between different applications.

Some key points about DXF and DWG formats:

• DXF is an open source file format developed by Autodesk in 1982 as the native format for AutoCAD
• DWG is a proprietary binary file format used in AutoCAD and other CAD programs
• Both are vector image formats that can contain 2D or 3D data
• DXF/DWG files retain details about lines, polygons, circles, text, dimensions and more
• Most CAD programs can import and export DXF and DWG files for compatibility

Comparison of DXF vs DWG

Feature	DXF	DWG
Type	Open ASCII or binary format	Proprietary binary format
Creator	Autodesk	Autodesk
Based on	AutoCAD’s native drawing format	AutoCAD’s native drawing format
Versions	ASCII: through AutoCAD Release 10 Binary: AutoCAD Release 10 and later	Many versions from AutoCAD R1.0 to 2018
Size	Larger than DWG	Smaller, more compressed than DXF
Read/Write Support	Supported by many CAD applications	Direct read/write limited to AutoCAD-based software

While DXF and DWG are closely related formats, DWG is more commonly used as the native format in AutoCAD and other programs. DXF is useful as an open exchange format between different CAD applications.

Common Issues When Exporting DXF/DWG Files

Exporting DXF or DWG files from CAD software seems like it should be a straightforward process. However, errors can occur that prevent a successful export. Some common issues include:

• Missing or corrupt CAD application components
• Incompatible or outdated software versions
• Insufficient user access permissions
• Interference from security software
• Bugs in the operating system registry

One particularly frustrating error that can occur when trying to export a DXF or DWG file is the “class not registered” error. This cryptic error message doesn’t provide much clue as to the underlying cause or how to fix it.

The “Class Not Registered” Error Explained

The full error message you may see when attempting to export a DXF or DWG file is something like:

“Class not registered looking for object with CLSID: {9A56B0CB-7EBE-4A74-8DCA-A30B6147E7C6}”

This indicates that a certain class or library required for AutoCAD functionality is not properly registered with the Windows operating system. Specifically, it often means the AcCtrl.dll or AcCtrl64.dll files are not registered.

Some other possible CLSID values referenced in the error include:

• {70B36D6B-5C73-493F-9184-9341A5222AF0}
• {B06140E0-5229-4360-9248-04DEDE2F45B6}
• {500D2909-D8FA-48EA-8F6B-8E7FB2A4DF2E}

But in general, they point to the same root issue – the AutoCAD libraries are not registered correctly in Windows. This is often caused by a corrupted Windows registry.

Why Does This Error Occur?

There are a few potential reasons why you may encounter the “Class not registered” error when exporting DXF/DWG files:

1. Incomplete or corrupted AutoCAD installation – If AutoCAD was not installed completely or some of its files have become corrupted, the necessary registration of its DLLs may fail.

2. Malware or viruses – Malicious software can damage system files and registry entries, causing errors like this.

3. Conflicting software – Other software that integrates with AutoCAD, like eTransmit, may conflict with the standard functionality if not configured properly.

4. User permission issues – If you are not an admin user in Windows, you may lack the necessary privileges to fully use and register AutoCAD components.

5. Bugs in operating system upgrades – Occasionally bugs have been reported in major Windows updates that can corrupt registry keys for Autodesk software.

Fixing “Class Not Registered” Errors

Fortunately in most cases this error can be resolved without too much technical difficulty. Here are some steps to try:

Step 1: Re-register AutoCAD DLLs

The first thing to attempt is manually re-registering the key AutoCAD libraries with the Windows registry:

1. Open an elevated Command Prompt (right-click > Run as Administrator)
2. Navigate to the AutoCAD installation folder, usually:
   32-bit: C:\Program Files (x86)\Common Files\Autodesk Shared\
   64-bit: C:\Program Files\Common Files\Autodesk Shared\
3. Enter these commands to unregister and re-register AcCtrl.dll:
   regsvr32 /u acctrl.dll
regsvr32 acctrl.dll
4. Do the same for AcCtrl64.dll if using 64-bit AutoCAD:
   regsvr32 /u acctrl64.dll
regsvr32 acctrl64.dll
5. Restart your computer for the changes to take effect.

This process will often clear up any registry corruption and allow DXF/DWG export to work again. If not, proceed to the next steps.

Step 2: Repair or Reinstall AutoCAD

If re-registering the DLLs alone doesn’t help, there may be a deeper problem with your AutoCAD installation. You can try repairing it:

1. Open the Windows Control Panel
2. Go to Programs and Features
3. Right-click on your AutoCAD version and select “Change”
4. In the setup dialog, choose “Repair” and follow the prompts

The repair process will attempt to fix any missing or corrupted files with the installation. If all else fails, you may need to fully uninstall AutoCAD and then reinstall it from scratch. Be sure to uninstall any associated software like eTransmit as well.

Step 3: Scan for Malware

On the chance that malware or a virus infection is causing the DLL registration error, you should run a full system scan with your antivirus/anti-malware tools. There are also specific tools to check for registry corruption from malware, like MalwareBytes Anti-Malware.

Step 4: Check for Software Conflicts

Conflicting third-party software can sometimes interfere with AutoCAD’s registration of its DLLs. Some known potential conflicts to check for:

• eTransmit for AutoCAD – Can prevent DXF/DWG writing if not configured properly. Try uninstalling it.
• Discord app – Some users have reported the Discord overlay causes this error. Disable the overlay feature.
• RealVNC Server – Known to conflict with accoreconsole.exe sometimes. Uninstall it if not needed.

You may need to do some trial and error here, disabling startup apps and services one by one until you can identify a conflict. Microsoft’s Autoruns utility can help manage all the different places apps can start up from.

Step 5: Contact Autodesk Support

If you’re still stuck after trying the above troubleshooting, it’s probably time to contact Autodesk’s official support channels for further assistance. They have more in-depth diagnostic tools and knowledge of more esoteric causes and fixes.

Be sure to provide them with details on your AutoCAD version, Windows version, any error messages you’ve recorded, and the troubleshooting steps you’ve already attempted. This will help them hone in on a solution faster.

Frequently Asked Questions

What does “class not registered” mean?

“Class not registered” is an error message indicating that a required component or library (in the form of a DLL file) is not properly registered in the Windows registry. This is often caused by registry corruption or an incomplete software installation.

How do I register a DLL file?

You can register a DLL by opening an elevated Command Prompt and running the command regsvr32 <path_to_dll>. To unregister, use regsvr32 /u <path_to_dll> first. Keep in mind this requires admin privileges.

Can I just ignore the “class not registered” error?

No, this error will likely prevent you from successfully exporting DXF/DWG files from AutoCAD. The underlying registry issue needs to be resolved to restore functionality. Ignoring it will just lead to more frustration.

Why does re-installing AutoCAD help fix the error?

Re-installing AutoCAD ensures that all of its files and registry entries are completely refreshed, overwriting any that had become corrupted. When done cleanly this can often clear up DLL registration issues.

Is there a way to prevent this error in the future?

Following some best practices can minimize the risk of registry corruption and “class not registered” errors:

• Keep Windows and AutoCAD updated to get bug fixes
• Allow AutoCAD’s installer to fully complete
• Don’t manually delete/move AutoCAD files and folders
• Run anti-malware scans regularly
• Avoid installing conflicting third-party software

But even with precautions, Windows registry issues can still sneak through sometimes. The troubleshooting steps covered above should get you back on track when they do.

Conclusion

Hitting a “class not registered” error while trying to export a DXF or DWG file from AutoCAD is undoubtedly frustrating. The cryptic error message doesn’t make it obvious that the underlying cause is an incomplete registration of AutoCAD libraries in the Windows registry.

Manually re-registering the problematic DLL files (often accrctrl.dll and accrctrl64.dll) using the regsvr32 utility is the first troubleshooting step to attempt. If that alone doesn’t help, repairing or reinstalling AutoCAD, scanning for malware, and checking for conflicting software are the next things to try.

In most cases, one of those steps will resolve the “class not registered” error and allow you to export DXF and DWG files again without issue. But if all else fails, Autodesk’s official support channels are there to help with their in-depth AutoCAD knowledge and diagnostic tools. They’ll get you back up and exporting in no time.