How to fix “This file type requires a Microsoft 365 subscription to open” for .msg files
This appears in the new Outlook when you open a saved .msg file. The new Outlook cannot open legacy Outlook message files on its own, so it asks for a Microsoft 365 subscription even if you already have one. The reliable fix is to open the file in classic Outlook. Jump to your situation below or work through the methods in order.
By Neeraj Singh ~8 min Updated Jun 2026 95% found this helpful
Error message
Sorry, the file 'message.msg' couldn't be opened. This file type requires a Microsoft 365 subscription to open. Get Microsoft 365.
Summary
This message comes from the new Outlook for Windows, which is web-based and cannot natively open legacy .msg files that were saved by classic Outlook. Rather than open the file, it prompts you to get a Microsoft 365 subscription, which is why people who already subscribe still see it. The dependable fix is to open the file in classic Outlook by right-clicking it and choosing Open with, then setting classic Outlook as the default for .msg files. If you only have the new Outlook, the signed-in account must be a Microsoft mailbox set as the primary account and linked to an active Microsoft 365 subscription, and the file must be under the 14 MB limit. As an alternative you can convert the .msg to .eml and import it into the new Outlook, or open it in a free third-party viewer. A quick or online repair of Office helps when the file association is the real problem.
What this error means
The new Outlook is a free, web-based app that handles live mailboxes well but does not natively open saved Outlook items. A .msg file is a classic Outlook format, so when you double-click one the new Outlook cannot read it and instead shows the Microsoft 365 subscription prompt.
That prompt is misleading, because an active subscription on its own does not make the new Outlook open .msg files. The file opens cleanly in classic Outlook, which is still the right tool for saved messages. So the fix is about which app handles the file, not about your subscription.
Common causes
The new Outlook is web-based and cannot open legacy .msg files on its own.
Windows is opening .msg files with the new Outlook instead of classic Outlook.
The signed-in account in the new Outlook is not a Microsoft mailbox set as primary.
The Microsoft 365 subscription is not linked to the mailbox the new Outlook uses.
The .msg or .oft file is larger than the 14 MB limit the new Outlook allows.
Classic Outlook is not installed, so there is no app that opens .msg directly.
The file association for .msg is broken after an Office update.
Expert insight
“This one frustrates people because the error blames their subscription, and they have a subscription, so they go in circles. The truth is simpler: the new Outlook just does not open saved .msg files. I tell everyone the same thing, right-click the file, open it with classic Outlook, and set classic Outlook as the default for .msg. If classic Outlook is gone from the machine, the clean workaround is to convert the .msg to .eml, which the new Outlook can import. Chasing the subscription message is a dead end, it is an app problem, not a licence problem.”
Manager, Tech Support & Operations · 19+ years fixing Windows and system errors
✓ How to fix it
Method 1
Open the file in classic Outlook
1Right-click the .msg file in File Explorer and choose Open with.
2Pick Outlook (classic) from the list. The file opens straight away because classic Outlook reads .msg natively.
3If classic Outlook is not listed, it may not be installed, see Method 6.
Method 2
Set classic Outlook as the default for .msg
1So double-clicking works every time, set the association. Right-click a .msg and choose Open with, then Choose another app.
2Select Outlook (classic) and tick Always use this app to open .msg files, then click OK.
3You can also set it in Windows Settings, Apps, Default apps, by searching for the .msg file type.
Method 3
If you must use the new Outlook, check the account
1Open the new Outlook, go to Settings, then Accounts, and confirm your primary account is a Microsoft mailbox such as an outlook.com address.
2Make sure that mailbox is linked to an active Microsoft 365 subscription.
3Keep the file under 14 MB, since the new Outlook will not open larger .msg or .oft files.
Method 4
Convert the .msg to .eml and import it
1The new Outlook can read .eml files. Convert the .msg to .eml with a free converter or by re-saving from classic Outlook.
2In the new Outlook, go to View, View settings, Files, Import, then Email files (.eml).
3You can also drag a saved .eml straight into a new Outlook folder.
Method 5
Open the file in a free .msg viewer
1If you only need to read the message, a standalone .msg viewer opens the file without Outlook at all.
2Free viewers and File Viewer Plus both read .msg and show the body and attachments.
3This is handy on a PC that has no Outlook installed.
Method 6
Repair or reinstall classic Outlook
1If classic Outlook is missing or .msg files still misbehave, repair Office. Open Control Panel, Programs and Features, select Microsoft 365 or Office, choose Change, then Quick Repair.
2Run Online Repair if Quick Repair does not help.
3If classic Outlook is not on the PC at all, install it from your Microsoft 365 account so .msg files have a native app.
The subscription prompt is misleading. An active Microsoft 365 subscription does not, by itself, make the new Outlook open saved .msg files, because the new Outlook does not support that format the way classic Outlook does. Open the file in classic Outlook, or convert it to .eml. Do not buy or renew a subscription expecting it to fix this, it will not.
Frequently asked questions
Why does Outlook ask for a Microsoft 365 subscription to open a .msg file?
Because the new Outlook is web-based and cannot open legacy .msg files on its own, so it shows a subscription prompt. The fix is to open the file in classic Outlook, not to buy a subscription.
I already have Microsoft 365, why do I still get this error?
An active subscription does not make the new Outlook open .msg files. The format is a classic Outlook format, so open the file in classic Outlook or convert it to .eml.
How do I open a .msg file in classic Outlook?
Right-click the file, choose Open with, and select Outlook (classic). To make it permanent, set classic Outlook as the default app for .msg files.
What is the .msg size limit in the new Outlook?
The new Outlook will not open .msg or .oft files larger than 14 MB, even when everything else is configured correctly.
Can the new Outlook open .msg files at all?
Not reliably. It can read .eml files, so the practical path is to convert the .msg to .eml and import it, or use classic Outlook or a viewer instead.
How do I stop the prompt coming back?
Set classic Outlook as the default app for .msg files so double-clicking always uses it, rather than the new Outlook.
Still not working?
If classic Outlook is not available and conversion is not practical, a dedicated .msg viewer will let you read and export the message without any Outlook or subscription. For a mailbox full of saved .msg files, a bulk .msg to .eml or PST converter can migrate them all at once. You can also submit your error to us for a tailored fix.
