AutoCAD 2017 “Drawing file is not valid” from network

[Brian1888]

Hi,
I have a customer using AutoCAD 2017 who is getting this error “Drawing file is not valid” when trying to open ANY DWG files from a network drive (server in remote location).
The files are not corrupted as if he copies the file to his local hard drive they all open ok. (His O/S is Windows 7 Pro)
They recently got a new SonicWall firewall installed and I assumed this was related but even after turning off all the security services (gateway anti-virus, anti-spyware, IPS [Intrusion Prevention]) etc it still gives the same error for all files.
I also disabled McAfee anti-virus software and Windows Defender.
I got SonicWall support to examine logs and packet traces and they have confirmed that the firewall does not see any packets being dropped, no issues with communication to the remote server or opening any other types of files from the network drive (eg PDF, Word, Excel etc)
The actual DWG files are quite small, most are between 100-200kb.
Any ideas what could cause this issue or any suggestions on what else I could try to attempt to resolve this?

Thanks!

Brian

[Ed Jobe]

Does he have write rights to the folder? In order to open the file, acad will have to create lock files, *.dwl. Try going to Windows Explorer, right click and add NEW> Text Document.

[Brian1888]

Hi Ed,
Thanks for the suggestion - yes he definitely has write permissions - I have copied files in to some of the folders, created copies of files for testing and just now created a blank TXT file

[rkmcswain]

You do not need WRITE access to the folder containing the drawings.
AutoCAD can open files in Read-Only folders with no issues.
The .DWL (and .DWL2) files are NOT lock files. File locking is handled by the server O/S.

@Brian1888 - what are the specs of this remote server? Is the storage some sort of NAS / SAN ? Anything other than a plain old Windows server O/S with internal storage?

[Brian1888]

Hi rkmcswain,
Thanks for the reply - the remote server O/S is Windows Small Business Server 2011 Standard SP1 and there is no SAN/NAS, just normal internal storage....
Thanks

[rkmcswain]

If you have not already done so, contact Autodesk Support and open a ticket (https://knowledge.autodesk.com/customer-service/account-management/subscription-management/support-options/web-support/submit-view-cases), get them involved. This is not normal behavior.

[Brian1888]

ok will do, thanks