topic Re: ...being accessed by another session. in AutoCAD Forum

...being accessed by another session.

LyleHardin — Tue, 10 Mar 2026 18:50:32 GMT

I know this has been mentioned before and there's even a knowledge base on it, but nothing we've tried has worked. Three of us in the office (out of over a couple dozen) get this message once in a while, usually after working on a file for several minutes. "Unable to save to drawing 'xxx' as it is being accessed by another session. Drawing saved to (local temp file).

We've narrowed it down to AutoCAD 2026. If we install and use 2025, the problem goes away. But using 2026 again, it returns eventually. Seems totally random.

Does anyone have any clues??

Re: ...being accessed by another session.

paullimapa — Tue, 10 Mar 2026 19:12:06 GMT

I've encountered this before when there's a sudden interruption with the network connection which causes the Windows OS to drop the mapping to the network drive. To eliminate the network being the issue, I would run a test by having all the dwgs stored locally and work from there for a day. If the problem does not occur even while running 2026 then the problem has to do with your network infrastructure.

Re: ...being accessed by another session.

pendean — Tue, 10 Mar 2026 19:14:42 GMT

@LyleHardin Do this test (and confirm both your PC/Laptop OS and where you all store your files, if WinServer or online and brand or something else)

Have 2 or 3 testers close their AutoCAD2026 session.
Have 1 tester open a file, do something, QSAVE and close the file but leave their AutoCAD open.
Have the other tester(s) open that same file, do you see the error?
Repeat with the other testers.

Re: ...being accessed by another session.

LyleHardin — Thu, 12 Mar 2026 20:45:21 GMT

We're pretty sure it's not a drawing lock thing. It will happen on files no one has touched for a long time and when only one person is working on them.
If we can't save a file, we'll do a SAVEAS, then delete the file we couldn't save to, and do another SAVEAS to save it back to the original name. So, we can do what we want with the file on the network, but AutoCAD just refuses to deal with it. We cannot do a direct SAVEAS back to the original file until we've erased it. The dwl files behave as expected as we open and close the files as well.
Autodesk has not been helpful when we opened the ticket with them.
We may just have to try working on files locally (hate doing that) just to see what happens. But it happens so infrequently that if it doesn't happen... well, how will we know that's the issue? We'll only know if it does happen while working locally, I guess.

For instance today, I've worked on a dozen files all day long with AutoCAD 2026 with no issues.

Re: ...being accessed by another session.

pendean — Thu, 12 Mar 2026 20:51:47 GMT

@LyleHardin wrote:
...But it happens so infrequently...
...For instance today, I've worked on a dozen files all day long with AutoCAD 2026 with no issues.

That tells me you have something local at play unique to your file location(s) or system in the office most likely, especially since I suspect also working with files locally (on each PC) will work without issues. If it was software based you'll see the problem regularly and can repeat on demand.

How deep a dive has your I.T. folks jumped into it? Your solution needs to be from them most likely. And if 2025 works 100% of the time for you folks and that's been verified, it may be time to rollback as an option.

Re: ...being accessed by another session.

catherine.watson — Tue, 17 Mar 2026 18:35:58 GMT

Hi @LyleHardin, I am sorry to hear this issue has been persisting for so long. Following @pendean's line of thought, if the issue does not happen when files are locally saved, this issue is most likely related to AutoCAD's interaction with your environment. A couple questions to help us narrow this down:

Have you done a true local save test? See below:
1. Create a transmittal of the file and save it to you and your colleagues' downloads folders to create fully local copies of the file and its supporting files.
2. Test opening the files on multiple devices to see if errors are produced.
  Note: The expected result is that these locally saved files behave as individual files and do not produce any errors. If this does not occur, let us know.
Do you have any antivirus, security, or registry cleaner programs installed?
Where are your files stored?
Are you and the other affected users the only three who work in office or are there others in office or remote who are experiencing the issue?

Thanks, and I look forward to hearing from you!

Re: ...being accessed by another session.

catherine.watson — Wed, 18 Mar 2026 22:28:06 GMT

Hi @LyleHardin, Checking in here; do you still need assistance with this issue? If one of the solutions above did the trick, please click “Accept as Solution" to help others with similar questions find the answer more easily.

Re: ...being accessed by another session.

rgrainerVXXAM — Thu, 19 Mar 2026 02:59:09 GMT

I feel your pain. This happens to me regularly, not everyday, but when it happens it occurs throughout the day. Not on a network, all files local, Windows 10. The only fix for me is to saveas, exit and saveas back over the original file upon restarting acad.
I also have and have had the constant spinning wheels showing when I hover over my windows task bar thumbnails ever since installing 2026. There are all kinds of other issues that really bug me in this version, and do not appear to happen in 2025 either, but I don't want to derail your post. Here's hoping C3D 2027 is a better product.

Re: ...being accessed by another session.

LyleHardin — Thu, 19 Mar 2026 14:00:30 GMT

No derailment here. Thanks for the response. I've not had the time to try working on local files. (Kinda glad to hear it happens to you.... sorry, lol). Misery loves company and all that.

I'm nearly 100% sure it's a 2026 thing. I can work in 2025 all day with no issues. I'll decide to try 2026 just for the heck of it and BOOM, it happens. Maybe not immediately but eventually, and sometimes, yes, immediately. IT has been keeping an eye on it looking for locks and even checking with Panzura but nothing ever shows up out of the ordinary.

I'm hoping a hot fix or something comes out and fixes it. We're on Windows 11 and it's only happened to 3 of us in the office out of about 30 users. Do you have any custom setups? We have a custom company menu installed, but again, it doesn't seem to affect 2025.

Re: ...being accessed by another session.

LyleHardin — Thu, 19 Mar 2026 14:04:55 GMT

We've not done a true local test. Sorry. Hesitant to do that on project files that others may need to work on.
Yes, we do have antivirus, security, but no registry cleaners. IT has helped me with all that to no avail.
Our files are stored on a LAN, but they are shared to two other offices in the country via Panzura. We've been looking at that too with no clues.
The three of us affected are really no different than other users. two of us have laptops, while I'm on a desktop. We alternat working at the office or remoting in. And there does not seem to be a pattern with that either.

Re: ...being accessed by another session.

mart.wagner — Thu, 19 Mar 2026 14:48:32 GMT

Maybe a network problem or the DWG file (folder) is being synchronized by OneDrive or Google Drive.

Re: ...being accessed by another session.

catherine.watson — Sat, 21 Mar 2026 01:32:28 GMT

Hi @LyleHardin , Thanks for the updates! That is bizarre that it is only happening to 3 of you, if it was antivirus or file storage related, I would expect the issue to be affecting most users. Have you seen the following article "Unable to save to drawing [path\filename].dwg(dxf)" when saving a file in AutoCAD products? As you can see most of the causes of this issue are environmental, but there are a few things that might fit with the troubleshooting you have done so far:

Do you have any AutoCAD plugins installed?
Are your drawing folder file paths added to AutoCAD Supported file search path? See how to do this below:
1. Open Options in AutoCAD (type OPTIONS in the command line).
2. Go to the Files tab.
3. Expand Support File Search Path.
4. Click Add.
5. Click Browse and select the folder you want to add.
6. Click OK, then Apply and OK again to save changes.
I would highly recommend doing a local file save test as this will help us narrow down what could be causing this issue. Since you'll be creating a local copy of the file, this should not affect the copy on your network used by your colleagues.

Thanks, and I look forward to hearing from you!

Re: ...being accessed by another session.

rgrainerVXXAM — Sat, 21 Mar 2026 03:37:34 GMT

Truth be told i was glad (sort of) that someone else has the problem. Hello misery!
Like you, I can open open earlier versions of my C3D , 2023-2025 and have no problems in them.
I think I Autodesk really dropped the ball on this version, it's really quite a big let down and dissappointment.

No one ever complained in the Civil forums, so I thought maybe It's just me that's having all this fun. I have been seeing a few other posts recently of folks complaining about various performance issues (lock ups, lagging etc). Saw an architect complain that this was the worst version of acad software he's seen and wants his money back or a rebate. I feel his pain too.

Re: ...being accessed by another session.

LyleHardin — Tue, 24 Mar 2026 15:09:38 GMT

- No AutoCAD plugins. We do use a custom, in house cuix file for running some scripts, accessing blocks & templates, and running custom LISP routines. The same menu is used for 2025 which has no issues.

- No, we do not include our drawings' folders in our AutoCAD File search path. That seems ridiculous, as we work on hundreds of projects. What would be the reason for doing that? We do have some extra paths included for custom menus, lisp routines and templates, but they are the same as 2025 which has no issues.

- If/when I get a chance or have to work on an AutoCAD project that no one else is working on, I'll try the local copy test. But, as you can see from another user here on this thread, they work locally and are having the same problem.

Re: ...being accessed by another session.

catherine.watson — Thu, 26 Mar 2026 19:29:52 GMT

Hi @LyleHardin, Thanks for these updates.

The reason for adding project folder paths to AutoCAD’s Supported File Search Path is to help AutoCAD more easily locate files stored on network drives or shared locations, not just local folders. This can prevent missing file errors and ensure consistent access to project resources across multiple users or workstations.

It’s usually not necessary, but in some non-local environments it can make a noticeable difference. Since we don’t yet know if the issue is occurring locally on your machine, you can hold off on testing this for now until we confirm whether it is specific to non-local files.

Another user experiencing this issue locally may have the same cause, or it could be something entirely different, as this issue can stem from multiple factors and each environment is unique. That said, we can quickly narrow this down with a simple local file save test.

If the issue is occurring locally, here are some steps you can take (pulling mainly from this article: DWG files unexpectedly become read-only and cannot be saved in AutoCAD or Civil 3D)

Configuration and settings within AutoCAD
- Define the default location for BAK files to a local path. Enter MOVEBAK on the command line and navigate to the desired location.
- Disable saving a backup file. Enter ISAVEBAK on the command line and change the value to 0 (zero).
- Stop appended saves and make sure that the full file saved each time. Enter ISAVEPERCENT on the command line and set the value to 0 (zero).
- Turn off registered app loading for custom objects. Enter DEMANDLOAD on the command line and set the value to 0 (zero).
Files permissions
1. Check that correct permissions are set on DWG and BAK files, and hidden DWL and DWL2 files.
2. Confirm that full read-write-modify permissions are on the folder location being saved to.
Check for potential AutoCAD profile issues: Sign into AutoCAD on colleagues device who is not having the issue and test saving files.
Check for potential Windows profile issues: If possible, have a colleague who is not having the issue sign into your device and test saving files.
Note: A cleaner way to do this is creating a new Windows user profile but this is obviously more involved.

As you can see in the article, there is a lot of potential causes and troubleshooting steps. To avoid doing unnecessary troubleshooting I would highly recommend just confirming whether or not the issue is happening locally on your device as a start.

Thanks and I look forward to hearing from you.

Re: ...being accessed by another session.

catherine.watson — Mon, 30 Mar 2026 22:56:36 GMT

Hi @LyleHardin, Checking in here; do you need some more time and/or further assistance with this issue?

Re: ...being accessed by another session.

hgreeneB5PYA — Tue, 31 Mar 2026 17:02:04 GMT

We've noticed this issue with remote staff working across VPN. Changing the ISAVEPERCENT from 50 (out-of-box setting) to 0 seems to fix the issue.

https://www.autodesk.com/support/technical/article/caas/sfdcarticles/sfdcarticles/ISAVEPERCENT-system-variable-affecting-file-size-performance-and-interoperability.html