"Drawing file is not valid": causes and fixes
AutoCAD and other CAD programs show "Drawing file is not valid" when they cannot read a DWG. Usually the file is damaged, incomplete or not really a DWG. Here is how to find out which, and how to get the drawing back.
First, check what the file is
Drop it into the DWG version checker. It reads only the first bytes, in your browser.
- It shows a version code such as AC1032 or AC1027: the file is a real DWG, and the damage is further inside. Go to the fixes below.
- It says the file is not a drawing: it was cut off, renamed, zipped or is a different kind of file. See "The file is not really a DWG".
Common causes
Why does a DWG say "drawing file is not valid"?
The most common causes are an incomplete download or email attachment, a file saved while the program crashed or the network dropped, a file renamed to .dwg that is really something else, and a file saved by software that writes DWG incorrectly.
Is it caused by the file being too new?
Usually not. A file from a newer version normally gives a different message about an incompatible version. See DWG created by an incompatible version.
Fixes, from quickest to slowest
1. Get a fresh copy
Check the file size. A drawing of 0 bytes or a few kilobytes is broken. Ask the sender to send it again, zipped or through a file-sharing link, because email systems sometimes cut off or block DWG attachments.
2. Open it in a different program
Programs read damaged files differently. Try the free DWG viewer here: if it opens, save the drawing as a PDF straight away.
3. Use the backup file
AutoCAD keeps the previous save as a .bak file in the same folder. Copy it, rename the copy from .bak to .dwg and open it. You lose only the changes since the last save.
4. Look for an autosave file
Autosave files end in .sv$ and are kept in the temporary folder set in the program's options. Copy one, rename it to .dwg and open it.
5. Run Recover in AutoCAD
If you have AutoCAD or a similar CAD program, use the RECOVER command (or "Drawing Utilities > Recover") instead of a normal open. It repairs what it can and reports what it fixed. Run AUDIT afterwards.
6. Insert it into a new drawing
If Recover fails, start a new drawing and insert the damaged file as a block, or attach it as an xref. This sometimes brings back the geometry when the file's header is damaged.
The file is not really a DWG
- It is zipped. Names like drawing.dwg.zip, or a file that is really a zip, need unzipping first.
- It is a different .dwg. A few unrelated programs use the .dwg ending.
- It is a DXF or PDF that was renamed. Rename it back and open it as that kind of file.
More reasons a drawing will not open are on DWG file won't open.