OneDrive 1 Million-Item Sync Preview: Windows 11 Requirements, 300K Performance Limits and Path Fixes

Before you plan around that number, read the conditions. The million-item ceiling is a public preview. It only applies to devices that meet hardware requirements and are enrolled in the Insider ring. Every other PC stays at the old limit. This isn't a new limit for every OneDrive user.

What the million-item limit actually is​

The new ceiling is counted per sync instance, per device, and the Windows preview has been around for months. Microsoft's Message Center notice MC1294528 said the Windows sync client would support syncing up to 1 million items per device starting in Public Preview in late April 2026. Microsoft's "Restrictions and limitations in OneDrive and SharePoint" support page says the rollout started on April 22, 2026.

The change is now coming to the Mac as well. In a newer notice, MC1477187, Microsoft says it is increasing the same item sync limit for OneDrive on macOS: from 300,000 items to 1 million items per sync instance, per device. The Mac preview's rollout will begin in mid-October 2026 and is expected to complete by late October 2026. That lines up with the event. Mac users with very large libraries now get the same deal Windows users have had since spring: a preview first, then later in General Availability.

One detail that's easy to miss: an "item" isn't just a file. In a third-party benchmark, OneMount pointed out that Microsoft counts the sync limit in items — files and folders together. If your library has a deep, heavily nested folder tree, you'll reach the limit sooner than your file count suggests.

Summary: The limit is real, but it's a preview. It counts files and folders together, it applies per device, and on Windows it has been available since late April.

Who qualifies for the Windows preview​

Microsoft's restrictions page lists these requirements for the million-item preview on Windows:

Microsoft attaches these caveats to the preview:

• VDI isn't supported. If your users work on virtual desktops, this doesn't apply to them yet.
• Read-only files and legal hold aren't optimized. Microsoft says performance isn't yet tuned for large numbers of read-only files or for accounts under legal hold, and that it's working on both.
• Devices that don't qualify keep working as before. Microsoft says devices that do not meet the minimum hardware and configuration requirements will continue to sync at the existing 300,000-item supported limit without disruption.

Note the absence of Windows 10 from the list. Older 8 GB laptops and hard-drive machines are also out. This is aimed at newer, well-specified Windows 11 hardware.

The 300,000 recommendation still stands​

Microsoft's own documentation creates some tension here. The same support page that describes the million-item preview still says that, for best performance, you should sync no more than 300,000 items in total across your cloud storage. It also warns that performance problems can start above that level even if you aren't syncing every item.

So the supported maximum has gone up, but Microsoft's performance advice hasn't. Should you sync a million items just because you can? Not before you test it.

OneMount's benchmark gives a sense of what happens in practice. The company tested OneDrive with a 997,392-item SharePoint library: 52 minutes to sync, 3.6 GB of RAM, and 238 minutes of checking for changes. It also reported that during that long "Looking for changes" phase, 44 of 45 attempts to open a file during that phase timed out. OneMount sells alternative sync software, so it has a stake in OneDrive looking clumsy. Its results are one vendor's test, not Microsoft data. Even so, the takeaway seems sound: the initial sync is only part of the picture. Rescans after sign-in or reboot can matter more day to day.

An admin also raised a fair question in the comments under Microsoft's April OneDrive blog post. They asked what happens when users go past the new limit, and described cases where exceeding the 300,000-item limit led OneDrive to delete files automatically. The comment is an unverified user report and Microsoft didn't answer it in what we reviewed. Still, it's a good reason to monitor libraries near any limit instead of assuming the sync client will handle it gracefully.

Summary: The ceiling has gone up, but the performance advice hasn't. Pilot on real hardware, watch the post-sync scan times, and treat 300,000 as the comfortable level.

Don't mix it up with other OneDrive limits​

The million-item number is one of several separate limits. Microsoft's support documentation lists these:

• Website copy limit: the OneDrive website copies at most 2,500 files at a time.
• Individual file size: 250 GB maximum for upload, download and sync.
• Sharing: a shared folder can contain at most 50,000 sub-items.
• Accounts per device: one personal OneDrive account and up to nine work or school accounts.
• Storage quota: a separate issue altogether. Neowin noted that a million-item sync limit doesn't help if your plan lacks the space, particularly after recent changes to the Family plan.

Long file paths: a shorter folder name helps​

Neowin also reported that a long-delayed fix for path-length errors has arrived: admins can now give the OneDrive folder a shorter custom name. Microsoft's file-path guidance explains why that matters. A work or school sync root such as C:\Users\JaneDoe\OneDrive - Contoso uses up characters before any of your folders even start. The longer your organization's name, the less room users have. Microsoft's guidance says admins can change this with the "Set a custom name for the OneDrive folder" Group Policy.

That gives users more room, but it doesn't remove Windows' path limits. Microsoft's path table shows:

• 260 characters for File Explorer and Office desktop apps. This is the limit most people actually hit.
• 400 characters for paths in OneDrive and SharePoint cloud storage.
• 520 characters for OneDrive sync: up to 400 for the path plus up to 120 for the OneDrive root folder.

Turning on the Windows long-path policy doesn't fix this. Microsoft says File Explorer and Office desktop apps don't currently opt in to extended-length paths, so they're still capped at 260 characters.

Finding paths that are too long​

Microsoft's guidance includes a PowerShell check. Point it at your OneDrive folder and it lists every path over 260 characters:

Get-ChildItem -Path "C:\Users\JaneDoe\OneDrive - Contoso" -Recurse |
Where-Object { $_.FullName.Length -gt 260 } |
Select-Object FullName, @{Name="PathLength";Expression={$_.FullName.Length}} | fl

Microsoft's suggested fixes are:

1. Shorten file and folder names, and keep folder structures shallow.
2. If a path is too long to rename in File Explorer, rename the item on the OneDrive or SharePoint website instead.
3. Keep your most-used files within one or two levels of the root.
4. Open files with very long paths in the browser, where the 400-character limit applies.

Neowin also said changes to how paths are calculated should mean fewer errors with shortcuts. We couldn't find official Microsoft technical documentation for that change, so treat it as reported until Microsoft publishes details.

A dedicated Shortcuts folder​

Shortcuts to shared folders have been cluttering the root of My Files for years. According to Neowin, Microsoft recently announced a dedicated Shortcuts folder to hold them. Users can still choose whether shortcuts go there or stay in the root. Neowin says the folder shows up on the web, in File Explorer, in Finder and in the mobile apps.

That helps with organization, but it doesn't change what shortcuts do to path length. Microsoft's guidance notes that when you add a shortcut to a SharePoint library or Teams channel, its contents sync beneath your OneDrive folder. Deeply nested shared libraries can push local paths past 260 characters fast. Microsoft suggests adding a shortcut to a subfolder rather than the whole library, and renaming long shortcuts after adding them.

What admins should do now​

• Check your hardware. List which machines meet the RAM, SSD, CPU and Windows 11/Server 2022 requirements before promising anyone a million items.
• Pilot through Insiders. The higher limit is preview-only. Test it on users who are near 300,000 items today.
• Leave VDI and legal hold accounts out. VDI isn't supported, and legal hold accounts aren't yet optimized.
• Plan for the Mac. With the macOS preview now rolling out, Mac users can be part of the same pilot.
• Deploy the folder-name policy. If your organization has a long name, this is the easiest fix for path errors on this list.

Raising the limit from 300,000 to a million items is a real improvement for organizations with large, long-lived SharePoint libraries. But it's a preview with hardware requirements, and Microsoft still recommends 300,000 items for the best performance. Run a pilot before you roll it out widely.