Fix the Outlook PST cannot be accessed error on network or removable storage. Move the PST file to a local disk first. Ask an administrator for folder permissions otherwise. Outlook 2016 build 16.0.7910.1000 added the cause. Microsoft does not support PST files on network shares. Steps follow the official page and were not tested here.
Outlook reports that it cannot open a PST file stored on a network share or removable storage. Microsoft names invalid file name and Access denied errors for this case.
Facts follow Microsoft Learn the article on adding PST or OST files from network storage. Microsoft lists Outlook 2019, Outlook 2016 and Outlook for Microsoft 365 and updated the page on October 5, 2026.
Why does Outlook Fail to Access a PST File?
Since Outlook 2016 build 16.0.7910.1000, Outlook calls the GetFinalPathNameByHandle Windows function to get the normalized path of the file. Windows converts a mapped volume path to UNC format and must open every folder in that path. Calls fail when you lack permission on any folder in the path.
How to Fix the PST Cannot be Accessed Error?
- Copy the file locally. Microsoft recommends moving the PST or OST file to a local disk and adding it in Outlook from there.
- Grant folder permissions. Administrators can give List and Read permissions on the restricted folders in the path so Windows can resolve it.
- Contact the storage vendor. Ask about changes that let Windows translate the storage path when you cannot move the file.
Microsoft states that adding PST files from a network share is not officially supported in Outlook 2016. Performance and stability risks apply when you continue.
What does Microsoft Not Say?
- Exact wording of the error dialog.
- Repair steps for a corrupt PST file.
- Steps for the new Outlook.
- Fixes for a PST file on local storage.
Related reading: how to fix an inaccessible Outlook data file and how to find a PST file in Outlook.
Frequently Asked Questions
Why does Outlook Say a PST File Cannot be Opened?
Microsoft says Outlook 2016 build 16.0.7910.1000 and later fails when you lack permission on a folder in a network path.
What is the Fastest Fix?
Move it to a local disk and add it from there. Microsoft lists this as the recommended step.
Can an Administrator Fix the Permission Problem?
Yes. Administrators can grant List and Read permissions on the restricted folders in the path.
Does Microsoft Support PST Files on a Network Share?
No. Microsoft states that adding PST files from a network share is not officially supported in Outlook 2016.
Does Microsoft Describe a Repair for a Corrupt PST File Here?
No. Microsoft describes a path and permission problem only.
Key Takeaways
- Local copies give the quickest fix.
- Folder permissions on the path can also fix it.
- Outlook 2016 build 16.0.7910.1000 added the path check.
- Network share PST files are not officially supported.
- This page does not describe a corrupt file repair.
Sources and References
Facts follow Microsoft Learn.
- Adding PST or OST files from network storage (Microsoft Learn) learn.microsoft.com