★★Why does ZWCAD fail to open certain DWG files and prompt "Invalid drawing file"

Issue:

ZWCAD can't open certain DWG files and prompts "Invalid drawing file".

Causes:

1. The DWG file was saved by a higher version of ZWCAD or AutoCAD.
2. The file is corrupted.
3. The file is encrypted.

Solution:

• When the file was saved by a higher version of CAD software:
  Users need to use the corresponding higher version of ZWCAD to open the file or convert the file into a lower version of DWG by the [DWG Converter] tool.
  
  1. 1. Open the DWG file with [Notepad], and check the first few texts for version number.
        
        AutoCAD R14    Version code：AC1014         
        AutoCAD 2000  Version code：AC1015
        AutoCAD 2004  Version code：AC1018         
        AutoCAD 2007  Version code：AC1021
        AutoCAD 2010  Version code：AC1024         
        AutoCAD 2013  Version code：AC1027
        AutoCAD 2018  Version code：AC1032
     2. Use the [DWG Converter] tool to convert the file into the proper version.
        [DWG Converter] is a free application provided by ZWSOFT, allowing users to batch convert DWG/DXF files from a higher version to a lower version, or the other way around.
        
        Click here to download [DWG Converter]
• When the file is corrupted:
  1. Execute RECOVER command in ZWCAD, and choose the file that needs to be opened.
  2. Follow the steps to recover the file. If ZWCAD still prompts "Invalid drawing file", it means the file is corrupted beyond repair.
• When the file is encrypted:

Contact the drawing provider to decrypt the file.