The operation cannot complete because of an unknown error [UNKN] when tring to open a DWG

[Joan29111648tlsz]

Hi, I've found a workaround for this, but I'm posting in case anyone knows a better solution (or needs a workaround.)

I've been opening DWGs made using Autodesk Civil 3d, without any problem for the last 2 years.
This week, my PC was upgraded to Win11 and I now have C3d 2026 and Illustrator both as fresh installs of the latest versions.
And suddenly I can't open DWGs without seeing the error in the title of this post.
The work around I've found is to save the DWG to Cad release2000 or to save as an r12 DXF. Those will now work.
I noticed that Illustrator's open dialogue no longer lists Autocad DWG. It lists Autodesk Trueview DWG.
Does Adobe no longer work with Cad release 2018 DWGs? (Which is the default version for C3d.)

I can export to older versions if I have to, but I'd rather fix it, if it's just a setting I need to alter somewhere.

Can anyone advise, please?

[Anubhav M]

Hello @Joan29111648tlsz,

I'm sorry to hear about your experience. Could you check if the files exported from C3D open fine on the latest version of AutoCAD? If yes, please share a link to a sample file here, along with screenshots of the settings used when exporting from your software and how it looks in AutoCAD, so I can check it on my end.

Looking forward to hearing from you.
Anubhav

[Joan29111648tlsz]

Hi,
Thanks.
As they were created in the latest version of Autodcad, by me, this morning, yes, they open fine in Autocad. However, dwg is not supported in this forum so I can't upload them, and company systems don't allow me to send a link to data saved on our onedrive. I can only share a link with people within our company. Or else I can email directly with attachments.

One saved as Autocad 2018 drawing. One saved as r2000.
The r2018 sets off the error message. The r2000 version opens fine. 

[Joan29111648tlsz]

 Here's the screenshot. The items were created using the commands pl, bpoly, and dtext. The things in the bottom left are blocks. The polylines are all 2d. There's nothing of a complicated or complex nature in the drawing.  

[Joan29111648tlsz]

I'm heading home soon and won't be back until Monday. Will catch up then.

[Anubhav M]

Hello @Joan29111648tlsz,

Kindly use a different file-sharing service to share a link to the file, so I can check this with the team.

Looking forward to hearing from you.
Anubhav

[Joan29111648tlsz]

I am not allowed to upload company files to unapproved sharing centres.
What I  have done is create an example file, containing nothing but randomly drawn polygons and uploaded it to a private onedrive. I will message you the link.

[Anubhav M]

Hello @Joan29111648tlsz,

Thanks for sharing the sample files. Kindly allow me some time to check this with the team.

Feel free to reach out if you have more questions or need assistance. We'd be happy to help.
Anubhav