Short answer. Windows can map a SharePoint Online library itself: File Explorer → This PC → Map network drive with the library's address (steps below). It works, but the connection drops every few hours and large files fail. OneDrive sync with a drive letter on top is stable, but the sync client has to track every item in the library on your PC. For a drive letter that stays connected without syncing anything, use a dedicated app such as OneMount.
Why a drive letter still matters
In an all-cloud world you'd expect the mapped drive to be a relic. It isn't — because a large amount
of real business software can only open a path, never a web address:
accounting and ERP systems, Access back-ends, CAD and engineering files linked by path, backup jobs,
batch scripts, scheduled exports. Give them https://…sharepoint.com/… and they simply
can't. Give them X:\Projects\… and they just work. That single fact keeps the drive
letter alive. (We lived the whole saga behind this — the
developer story is here.)
The ways to do it, at a glance
| Method | Drive letter | Stays connected | Large files | Copies to disk | Co-authoring |
|---|---|---|---|---|---|
| Windows built-in (WebDAV) | Yes | Drops after hours | 50 MB default, 4 GB max | No | Unreliable |
OneDrive sync + subst | Yes | Yes | Yes | Tracks every item | Yes |
| Browser only | No | Yes | Yes | No | Yes |
| Paid apps on Microsoft Graph | Yes | Yes | Usually | Cache | Often lock-only |
| OneMount | Yes | Renewed silently | Over 4 GB (Windows 11 24H2+) | Nothing in advance | Yes, with AutoSave |
Step by step: map SharePoint with Windows' built-in tool
No software to install. You need the WebClient service (on by default in Windows 10 and 11) and a few minutes:
- Copy the library address. Open the document library in your browser and copy the address up to the library name, for example
https://contoso.sharepoint.com/sites/Finance/Shared Documents. - Add SharePoint to Trusted sites. Internet Options → Security → Trusted sites → Sites: add
https://*.sharepoint.com. Without it Windows refuses to sign in to the drive automatically. - Sign in through Edge in Internet Explorer mode. This is the step most guides skip. Windows' WebDAV client doesn't see your sign-in from normal Edge or Chrome — only the sign-in cookie left by the Internet Explorer engine. IE itself is gone from Windows 11, so you use Edge's IE mode:
- Edge → Settings → Default browser → Allow sites to be reloaded in Internet Explorer mode: Allow, then restart Edge.
- Open the library, then … → Reload in Internet Explorer mode.
- Sign in and choose Stay signed in — without it the cookie disappears when the window closes.
- Map the drive. File Explorer → This PC → … → Map network drive, pick a letter, paste the address into Folder (Windows also accepts
\\contoso.sharepoint.com@SSL\DavWWWRoot\sites\Finance\Shared Documents), tick Reconnect at sign-in and click Finish.
The errors you'll most likely see
- "Access denied" or the drive asks for a password — Windows has no valid sign-in for SharePoint. Sign in again in Edge's Internet Explorer mode with Stay signed in (step 3) — a sign-in in normal Edge doesn't count.
- System error 224 — the SharePoint address isn't in a zone where Windows may sign in automatically. Add it to Trusted sites (step 2); in a domain, a Group Policy zone assignment can override your setting.
- The drive disconnects after a few hours — the sign-in cookie expired and Windows doesn't renew it. See below.
- "The file size exceeds the limit allowed" — the WebDAV client downloads up to 50 MB by default (a registry value raises it), and files over 4 GB never work.
- Some files are simply missing from a folder — you see them in the browser, but not in File Explorer. WebDAV measures the full network path,
\\contoso.sharepoint.com@SSL\DavWWWRoot\sites\…, not the shortX:\…you see, and once it passes about 255 characters Explorer silently hides the file: no error, no warning. The drive letter doesn't shorten it and enabling long paths in Windows doesn't help — only shorter folder and file names do.
The real catch: keeping the sign-in alive
The drive works only while that IE-mode sign-in cookie is valid — depending on your organization's policies, from a few hours to a few days. When it expires, nothing renews it: you open the library in IE mode again, refresh the page, and the drive comes back. On top of that, Edge forgets a page reloaded in IE mode after 30 days, so the setup itself has to be repeated.
It can be automated — a scheduled task that reopens the library in IE mode, an Enterprise Mode site list pushed by Group Policy, logon scripts such as OneDriveMapper. But each workaround leans on a retired browser engine, breaks as soon as multi-factor or Conditional Access asks for a fresh sign-in, and has to be maintained on every PC. Keeping the session alive without IE is exactly what OneMount does silently in the background.
Map OneDrive for Business as a network drive
OneDrive for Business is a SharePoint library too, so the same steps work. The address is your OneDrive
in the browser, for example https://contoso-my.sharepoint.com/personal/jane_contoso_com/Documents
(note the -my in the host name), and the trusted site is https://*-my.sharepoint.com
if your wildcard doesn't already cover it. It has the same limits: the session expires and large files
fail. OneMount finds your OneDrive automatically and mounts it next to your SharePoint libraries.
Where each method breaks
1 · WebDAV — "Map network drive"
FragileThe method above. In a clean demo it looks perfect; in daily use it's the most confusing one, because Microsoft has effectively wound it down. Sign-in still depends on the Internet Explorer engine, although Microsoft ended IE11 access to SharePoint and OneDrive in January 2023 — hence Edge's IE mode. And the session doesn't renew itself, so users hit "access denied" in the middle of work until someone signs in again (details above).
2 · OneDrive sync (with a drive letter on top)
Tracks everything
The sync client can put your library in Explorer, and you can even subst a letter onto
the synced folder. With Files On-Demand, file contents download only when you open them, so the disk
doesn't fill up — but the client still creates and watches a placeholder for every item, and that
brings the large-library problem back. Microsoft is rolling out support for up to 1,000,000 synced
items, yet still recommends staying under 300,000 and warns that performance issues can
occur above that even if you aren't syncing everything; first sync on a big library can
take the better part of a day, and "processing changes" can last for days.
We measured what happens at a million items.
3 · Just use the browser
No path for appsPerfectly fine for opening a document by hand. Useless for the software that needs a real path — the accounting system, the Access back-end, the CAD file, the backup job. They can't open a web address, and no amount of "just use the browser" changes that.
4 · Dedicated paid "drives" for SharePoint
Breaks the cloudThere are separate paid apps that promise SharePoint and OneDrive as a drive. They take away some of WebDAV's pain — but many break the very thing the cloud is for:
- Many require an Azure app registration. Before a single drive appears — admin consent and a project in the tenant. For a small company without an IT department, that's a stopper.
- Some break real-time editing. Instead of live co-authoring you get either a hard lock on the file for one person, or version conflicts for several.
- Some overwrite the version history. Every save pushes a whole new copy of the file to the cloud instead of editing the living document.
What actually holds up
Strip the failures into requirements and the answer is specific. A drive letter for SharePoint that survives real work has to:
- Mount without Internet Explorer — no dependency on a deprecated engine.
- Keep the session alive — renew authentication silently, so the drive doesn't drop every few hours.
- Sync nothing in advance — files are fetched when they're opened, so a terabyte library and its million files are a non-issue.
- Lift WebDAV's limits — no 4 GB ceiling per file, no 50 MB download cap, and no files hidden because their path is long.
- Preserve co-authoring and version history — the file on the drive has to be the live cloud document, not a copy that overwrites the cloud on every save.
- Need no Azure app registration — a normal Microsoft 365 sign-in, nothing for an admin to approve.
Want that drive letter without the WebDAV workarounds?
Install OneMount from the Microsoft Store, sign in with your work account, and your SharePoint and OneDrive libraries appear in File Explorer. 14 days free, no card.
How OneMount does it
OneMount is the tool we built to meet that list. It doesn't rely on Windows' fragile WebDAV client: on Windows 11 24H2 and later, each library reaches File Explorer through OneMount's own SMB layer running locally on your PC, so a file can be bigger than 4 GB, and the path is counted from the drive letter — files with long paths don't vanish from folders, and mounting a deeper folder makes paths shorter still. Sign-in is renewed silently in the background, and files are fetched only when you open them — nothing is synced ahead. Because the file on the drive is the live SharePoint document, Word and Excel open it with real co-authoring, AutoSave and full version history intact — the things the other approaches quietly switch off.
- Install — from the Microsoft Store, no admin rights.
- Sign in — your normal Microsoft 365 account; OneMount finds your sites and libraries itself. No Azure registration, no admin consent, no tenant setup.
- Work — the drives are in File Explorer, and every app that wants a path finally gets one. The trial starts automatically.
And for everyday work — a right-click menu in File Explorer: right-click a file or folder on the drive to copy the SharePoint web link (for outside people) or the drive path (for colleagues inside), open it in SharePoint, show its version history, send it to Outlook, or search the library in SharePoint. Rolling it out to a whole team? See deployment and Group Policy and installing Store apps with GPO.
FAQ
Can I map SharePoint Online as a network drive in Windows 11?
Yes. Windows' own Map network drive accepts a SharePoint library address, but the connection expires every few hours and large files fail. Apps like OneMount give you a drive letter that stays connected.
Why does my mapped SharePoint drive keep disconnecting?
The built-in mapping depends on a sign-in cookie from Edge's Internet Explorer mode that lasts from a few hours to a few days, and Windows doesn't renew it. When it expires, the drive drops or asks for a password until you sign in again in IE mode.
Is there a file size limit on a mapped SharePoint drive?
With Windows' WebDAV client, downloads stop at 50 MB by default and files over 4 GB can't be used at all. On Windows 11 24H2 and later, OneMount has no 4 GB limit.
Can I map OneDrive for Business as a network drive?
Yes, the same way: use your OneDrive address on -my.sharepoint.com. OneMount finds your OneDrive automatically and mounts it alongside SharePoint.
Do I need admin rights or an Azure app registration?
Not for OneMount: it installs from the Microsoft Store and signs in with your normal work account. The built-in method needs no software either, but Trusted sites settings may be managed by your IT department.
Keep reading
- The developer story behind OneMount — the terabyte library, the conflicted copies, the tools that flattened our version history.
- OneDrive and 1,000,000 files — sync test, speed and performance on a 997,392-item library.
- Create a SharePoint site for your organization — the library, permissions and sharing before you map it.
Sources
- Microsoft — Troubleshoot mapped network drives to SharePoint Online.
- Map SharePoint as a network drive: methods and real limits (WebDAV, IE dependency, expiring cookies).
- Microsoft — Restrictions and limitations (sync item guidance).
- Microsoft — Save disk space with OneDrive Files On-Demand.
- Microsoft — Allow sites to be reloaded in Internet Explorer mode (30-day local site list).
- Microsoft — Internet Explorer 11 support end dates.