According to Neowin, after upgrading the browser from one of previous versions to the version 155, Edge may fail to launch at all for users with existing browser profiles. This doesn't look like a crash after a few minutes or a frozen tab. On affected machines, Edge simply doesn't open.
What Microsoft has confirmed
As Neowin reports Microsoft's position, the main facts are:
- Cause: Microsoft says the issue is linked to a service-side change, although it hasn't explained exactly what was changed or why it caused Edge 155 to stop opening.
- Containment: The company has already rolled back the related service-side change, so the issue shouldn't be spreading anymore.
- Devices already hit: users who already updated their browsers before the rollback are still affected and might see Edge failing to launch on their managed devices.
- Permanent fix: The company is currently investigating a client-side fix. No patch version or release date has been confirmed.
The difference between those last two points matters. The server-side rollback should stop new cases. It does not repair PCs that were already affected. Those machines need manual work from an admin, or a client update that doesn't exist yet.
In short: new cases should have stopped, but devices that were already affected stay broken until an admin applies the workaround or Microsoft ships a client fix.
The workaround, and the one file you must keep
For devices that are already affected, Microsoft has published a workaround that administrators can implement to mitigate the issue. As reported, it has two steps:
- First, admins should disable the scheduled update restart task in the Microsoft Edge management service.
- Admins then need to delete the contents of the Microsoft Edge User Data\Policy folder, but leave the Primary Account file untouched so existing browser profiles aren't deleted.
A few cautions:
- Don't delete the whole folder. Delete the contents of the Policy folder, not the folder itself and not the User Data directory around it. The Primary Account file stays.
- Don't fall back on old troubleshooting habits. A common tip on community forums is to back up and delete Edge's entire User Data folder. One answer on Microsoft Q&A suggests going to %localappdata%\Microsoft\Edge\ and backing up User Data before you delete the folder from the path mentioned above. That approach removes far more than this problem needs, including the existing profiles that Microsoft's workaround is designed to protect.
- Missing details. The reported guidance doesn't give a full per-user file path, a script, or detailed portal steps. If you're automating this across many devices, check the exact steps against Microsoft's own advisory or support channel before you script it.
- Only fix broken machines. This is a fix for devices that won't launch Edge, not a preventive clean-up for every PC.
Why the Primary Account file matters (our analysis)
Microsoft hasn't explained the root cause, so the following is an informed reading rather than a confirmed diagnosis.
Microsoft's own documentation for the Edge management service describes a cloud-based policy system. Admins in the Microsoft 365 admin center assign settings, and users only receive them when they're signed into Edge. The same documentation says cloud policies only take effect when Edge restarts, and that on Windows, policies follow the primary account signed into the browser.
That helps explain the workaround:
- The Policy folder is where cloud-delivered policy data appears to live on the device. Clearing it gives Edge a clean policy state.
- Disabling the restart task likely stops the management service from triggering another policy-driven restart before things settle. This is our reading; Microsoft hasn't said why.
- Keeping the Primary Account file probably preserves the tie between the profile and the managed account. Remove it and you risk losing more than the bad policy data.
This also fits the reported scope: devices that are managed through the cloud service and have existing profiles. Microsoft hasn't given a breakdown by operating system or tenant configuration, though.
Who is likely affected
The reporting describes some enterprise users. Microsoft has given no numbers on how widespread the problem is.
- Managed devices on Edge 155: these are the devices at risk. Neowin notes that Microsoft released Edge 155 on October 8. Microsoft's Stable channel release notes list the main release as 155.0.4283.45 on that date. Follow-up builds 155.0.4283.60 (October 15) and 155.0.4283.62 (October 16) are listed only as general bug and performance fixes.
- Extended Stable: according to the same release notes, this channel is still on version 152. Organizations that keep users on Extended Stable shouldn't have moved to 155 yet, so they're outside the reported scenario for now.
- Home users: Neowin judges that since the issue affects managed enterprise environments, regular home users running Edge 155 probably won't be bothered by this problem. That's a reasonable expectation, not a Microsoft guarantee for unmanaged PCs.
Microsoft's public Stable channel notes for Edge 155 don't currently mention the launch failure or the workaround. Don't take that as proof either way. Release notes are often written before field problems appear.
How to tell this bug apart from other launch failures
"Edge won't open" can have many causes, and not every failure since October 8 is this bug. Microsoft's general troubleshooting guide lists typical symptoms, such as cases where the msedge.exe process appears in Task Manager, but no window opens, or where a blank Edge window appears briefly and then closes.
Other causes are possible too. In May, on Microsoft Q&A, one administrator reported that Edge 149+ will start again when disabling Trend Micro Security Agent. Graphics drivers, corrupted profiles and security tools are all familiar suspects.
The Edge 155 bug is most likely if all of these apply:
- The device is managed and the user signs in with a work account.
- The user has an existing profile, not a fresh one.
- The failure started right after the update to version 155.
If Edge fails in a brand-new profile, or on an unmanaged PC, look elsewhere first.
What happens next
Edge now releases a major version roughly every two weeks. Microsoft's release notes confirm Edge has completed the move to a 2-week cadence for updates, and Edge 156 is expected on October 22. Whether that release includes the client-side fix is unknown, and nobody should plan around it until Microsoft says so.
The faster cadence cuts both ways. Fixes arrive sooner, but so do regressions, and a policy-service change can break a browser without any new installer reaching the device. The Edge management service also sends policies from the cloud to a signed-in browser, so a mistake on Microsoft's side can reach devices directly. Here it apparently did.
Practical checklist for IT admins
- Triage: confirm the device is on Edge 155, is managed, and has an existing profile.
- Mitigate: disable the scheduled update restart task in the Edge management service, then clear the contents of the User Data\Policy folder while keeping the Primary Account file.
- Don't over-clean: avoid deleting the whole User Data folder, since that takes users' profiles with it.
- Watch: keep an eye on Microsoft's Edge release notes and admin advisories for the client-side fix, and remember to re-enable the restart task once the fix is out.
- Consider the channel: for critical groups, the Extended Stable channel buys time before new major versions arrive.
Bottom line: Microsoft has stopped new cases at the source, but PCs that were already affected stay broken until an admin applies the workaround or Microsoft ships a client fix. If you use the workaround, keep the Primary Account file.