How to Repair a Corrupted DWG File (Step by Step)

How to Repair a Corrupted DWG File (Step by Step)

ByOpenDWG Team

A corrupted DWG is every designer’s quiet fear. Hours or weeks of work, and the file won’t open, crashes AutoCAD, or opens with chunks missing. Your heart sinks.

Take a breath. Most corrupted drawings can be repaired, at least partly. Even when a file seems completely dead, a backup copy or an autosave is often sitting somewhere on the same computer, waiting to be found. AutoCAD has built-in tools made for exactly this, and there are a few tricks that work when those tools don’t.

This guide goes through repair methods from the gentlest to the most drastic. Work through them in order, and keep copies as you go.

Before you do anything: make copies

Repair tools change files. If a repair goes wrong, you want the original to try something else.

  1. Copy the damaged DWG to a new folder.
  2. Copy any matching .bak file too.
  3. Work only on the copies.

Also save your work to a local drive while repairing. Network and cloud folders add extra things that can go wrong.

Signs a DWG is corrupted

Corruption shows up in different ways:

  • “Drawing file is not valid” or similar errors on open
  • AutoCAD crashes when opening or saving the drawing
  • Objects disappear, or can’t be selected
  • Commands fail with strange errors
  • The file is suddenly much larger or smaller than usual
  • Saving takes far longer than it should

If the file won’t open at all, start by ruling out simpler causes. A half-finished download or a version mismatch can look like corruption. Our guide on fixing “drawing file is not valid” covers those checks.

Method 1: AUDIT (if the drawing opens)

If you can still open the drawing, start with AUDIT. It checks the drawing’s internal database and fixes errors it finds.

  1. Open the drawing.
  2. Type AUDIT and press Enter.
  3. When asked “Fix any errors detected?”, type Y and press Enter.
  4. Read the summary in the command line.
  5. Save the drawing under a new name.

Run AUDIT a second time. If the second run finds zero errors, you’re in good shape.

Method 2: RECOVER (if the drawing won’t open)

RECOVER is AUDIT’s big brother. It opens and repairs a drawing that won’t open normally.

  1. Start AutoCAD with a blank drawing.
  2. Type RECOVER and press Enter.
  3. Pick the damaged file.
  4. AutoCAD opens it and repairs as it goes.
  5. Review the report.
  6. Save under a new name.

If the drawing uses xrefs that may also be damaged, use RECOVERALL. It repairs the main drawing and every attached xref, and can save them all.

Method 3: PURGE

Corrupted drawings often carry junk: unused blocks, layers, styles and leftover data from other files. PURGE removes what isn’t used.

  1. Type PURGE and press Enter.
  2. Tick the options to purge nested items.
  3. Click Purge All.
  4. Repeat until nothing is left to purge.

For a deeper clean, type -PURGE with a dash, then choose R for registered applications. Regapps from old add-ons pile up and can bloat and slow down a file.

Save, then run AUDIT again.

Method 4: WBLOCK the good parts to a new file

WBLOCK writes objects from your drawing into a brand-new DWG. Only the objects you select travel across, so a lot of hidden damage gets left behind.

  1. Open the drawing.
  2. Type WBLOCK and press Enter.
  3. Choose Objects, then select everything you want to keep. For the whole model, select all objects in model space.
  4. Set the base point to 0,0,0.
  5. Choose a new file name and location.
  6. Click OK.
  7. Open the new file and check it.

You’ll need to recreate layouts and some settings in the new file. But the geometry is usually clean.

Method 5: Insert into a fresh drawing

If WBLOCK fails, try going the other way.

  1. Start a new drawing from a clean template.
  2. Use INSERT to bring in the damaged DWG as a block, at 0,0,0.
  3. Explode the inserted block once.
  4. Run AUDIT and PURGE.
  5. Save.

Method 6: A DXF round trip

Saving to DXF and back can strip out damage, because DXF is rewritten from scratch.

  1. Open the drawing, or recover it.
  2. Use Save As and choose DXF as the file type.
  3. Close the drawing.
  4. Open the DXF.
  5. Save it as a DWG under a new name.

This works surprisingly often for stubborn files. Check the result carefully, as a few special objects may change on the way through.

Method 7: Use the backup and autosave files

AutoCAD keeps two kinds of safety copies.

The .bak file. Created each time you save, holding the previous version. It sits next to the drawing. Copy it, rename the extension to .dwg, and open it.

Autosave files. Saved every few minutes while you work, with an .sv$ extension, in a temporary folder. In AutoCAD, the Drawing Recovery Manager lists them after a crash. You can also find the folder in Options, on the Files tab, under Automatic Save File Location.

Rename an .sv$ copy to .dwg to open it.

Method 8: Ask a colleague or the original sender

If the file came from someone else, they almost certainly have a working copy. If you’re in a team, check the project folder history or your company’s backups. Many network drives and cloud services keep previous versions of files. On Windows, right-click the file and check Properties for a Previous Versions tab.

When the repaired file is a different version

Repairs sometimes leave you with a file in a different DWG format from the original. That happens if you run them in newer software, or save to a DXF and back.

Before you send the repaired drawing on, check which format the other person needs. If they use older software, save a copy in their format. Our guide on checking a DWG file’s version explains the version codes.

Dealing with damaged xrefs

Sometimes the main drawing is fine and an attached xref is the broken part. The symptoms look the same: crashes, errors or missing areas.

Open the External References palette and look at each attached file. Detach any that show errors, then try opening the main drawing again. If it behaves, repair the xref on its own using the methods above, then reattach it.

RECOVERALL is built for this situation. It works through the main drawing and every xref in one pass.

Keep a repair log

If a drawing gave you trouble once, it may give you trouble again. Make a short note in the project folder: what went wrong, which method fixed it, and the date. Next time, you’ll know where to start, and so will anyone else on the team.

What about third-party repair tools?

There are commercial tools that claim to repair DWG files. Some work. Many are disappointing. Be careful with any tool that:

  • Asks you to upload private drawings to an unknown server
  • Charges before showing you any results
  • Comes bundled with other software

Try AutoCAD’s own tools and the methods above first. They solve most cases.

How to tell the repair worked

After repairing, check:

  • AUDIT reports zero errors
  • All layouts open and plot correctly
  • Xrefs load
  • Dimensions and text look right
  • The file saves quickly and at a sensible size

Open the repaired file in a second viewer too. Our online DWG viewer is a quick independent check that the file reads cleanly.

Why DWG files get corrupted

  • AutoCAD or Windows crashes during a save
  • Saving straight to a network drive or USB stick that disconnects
  • Cloud sync tools grabbing the file while it’s being written
  • Old add-ons writing unusual data
  • Copying and pasting content from damaged drawings
  • Failing hard drives

How to prevent it

  • Save locally, then copy to shared storage
  • Keep “Create backup copy with each save” turned on
  • Set autosave to every 10 minutes or so
  • Run AUDIT and PURGE regularly on long projects
  • Don’t copy content out of drawings that act strangely
  • Keep regular project backups

Questions people ask

Can I repair a DWG without AutoCAD?

Partly. You can recover .bak files and convert files with free tools. Proper repair with AUDIT and RECOVER needs AutoCAD or a similar CAD program.

Does RECOVER delete anything?

It can remove objects it can’t fix. That’s why you work on a copy.

My file is 0 KB. Can it be repaired?

No. A 0 KB file has no data. Look for the .bak file, autosave files or previous versions instead.

How do I stop the same drawing getting corrupted again?

Clean it with WBLOCK into a fresh file, then work only on the new file.

Finally, be patient with large files. RECOVER and AUDIT can take several minutes on a big drawing. Let them finish, even if AutoCAD looks frozen. Stopping halfway can leave the file in a worse state than before.

The short version

Copy the file first. If it opens, run AUDIT and PURGE. If not, use RECOVER. When that fails, WBLOCK the good parts out, try a DXF round trip, or fall back to the .bak and autosave files. For other opening problems, see our DWG file not opening checklist, and use our free DWG viewer to double-check the repaired file.

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