keeps saying access denied permission unable to share documents

The error indicates that the account trying to open the shared document or folder does not currently have valid permission to it, or is signed in with the wrong account.

Use these checks and fixes:

1. Confirm the correct account is used

• If a link was shared to a specific email address, that same account must be used to open it.
• Sign out of all Microsoft accounts in the browser, then sign in again with the account that received the sharing invitation and retry the link.

2. Check that permissions are actually granted

• The owner of the file or folder should open it in OneDrive or SharePoint and verify sharing:
  • For a site or folder: ensure the affected user (or a group they belong to) is listed with at least View or Edit permission.
  • If the user is missing, re‑share the file or folder to that user.

3. If the user was already granted access but still sees “Access Denied”

• The site/file owner or admin should:
  1. Go to the site → Settings → Site permissions.
  2. Use Check Permissions and enter the user’s name/email to see what access they actually have.
  3. If no appropriate permission is shown, grant access again to the file or site.
  4. If the error continues, remove the user from the site and then grant permissions again.

4. If the user cannot access a shared link specifically

• Remove the affected user from the site, then share the file or folder again so a fresh sharing link and permissions are created.

5. If the owner is using a folder share and still gets “Access Denied” for others

• On some SharePoint/OneDrive sites, the Limited-access user permission lockdown mode feature can block users from accessing a shared folder if they do not have access to the parent.
• Workarounds:
  • Share individual files instead of the folder, or
  • Share the whole site/subsite, or
  • If the site does not require this feature, disable Limited-access user permission lockdown mode at the site collection level (note that some publishing features may depend on it).

If the problem affects a guest account repeatedly, an admin can remove the guest from the Microsoft 365 admin center and from the site collection, then re‑grant access so the guest is recreated cleanly.

References:

• Access Denied or You need permission errors in SharePoint Online and OneDrive
• Unable to access SharePoint Online
• "Access Denied" error when trying to access a shared folder