Problem

File format and version of AutoCAD files
Older versions of MicroStation cannot open .dwg files that are created
with more recent versions of AutoCAD. A message is displayed saying:

XM and V8i versions:
[full path and filename] is not in a recognized file format

V8 2004:
[full path and filename] contains errors that prevent opening it.
Do you wish to attempt to recover the file by correcting these errors?

Solution

To find the file format version of the .dwg file, the following steps
can be taken.

- open the .dwg file with a text viewer or text editor (Be very careful: do NOT edit and/or save the file).
- although a .dwg is a binary file, the first characters in the filewill show:

ACxxxx. The xxxx represents the file format version.

In case you have received a .dxf file, the file format of the .dxf file,
can be found in this way:

- open the .dxf file with a text viewer or text editor (Be very careful: do NOT edit and/or save the file).
- search for the text line that starts with: $ACADVER. Below that line you will see: ACxxxx. Again xxxx represents the file format version.

The list below shows an overview of the file format and the version of AutoCAD in which it was introduced. From this list you can derive which Bentley product version you will need to open the .dwg or dxf:

DWG file header version codes

Format version numbers:

$ACADVER

AC1032 AutoCAD 2018/2019/2020/2021/2022/2023 Bentley 10.07.00.39 / 10.13.00.48 / 10.14.00.109 / 10.15.00.74 / 10.16.00.80/ 10.17.00.209

AC1027 AutoCAD 2013/2014/2015/2016/2017 Bentley 08.11.09 /

AC1024 AutoCAD 2010/2011/2012 Bentley 08.11.07 /

AC1021 AutoCAD 2007/2008/2009 Bentley 08.09.04 / 08.11.05
AC1018 AutoCAD 2004/2005/2006 Bentley 08.05.02 / 08.09.03
AC1015 AutoCAD 2000/2000i/2002 Bentley 07.01.05 / 08.01.00
AC1014 Release 14 (1997)
AC1012 Release 13
AC1009 Release 11/12
AC1006 Release 10
AC1004 Release 9
AC1003 Version 2.60
AC1002 Version 2.50
AC1001 Version 2.22
AC2.22 Version 2.22
AC2.21 Version 2.21
AC2.10 Version 2.10
AC1.50 Version 2.05
AC1.40 Version 1.40
AC1.2 Version 1.2
MC0.0 Version 1.0

The link below will also help you with the version numbers.:
AutoCAD Release History

http://autodesk.blogs.com/between_the_lines/autocad-release-history.html

MicroStation V8i SS2 and up make use of Autodesk's RealDWG libraries to allow for opening and editing AutoCAD files (.dwg / .dxf).
The RealDWG version used in MicroStation determines up to which version of AutoCAD is supported. If the version is RealDWG 2020, it means that up to AutoCAD 2020 file format is supported.

To find out which version of RealDWG is integrated with your version of MicroStation, open any dgn or dwg file in MicroStation and in the key-in window, enter:
version

In the status bar you will see the full version number of MicroStation as well as the version of RealDWG.

See also

Other language sources

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