When the new Outlook itself is broken, Windows has two official buttons for it — Repair and Reset. They are not equal, and picking the wrong one first costs you a full re-sync.
App problems deserve app tools. For the new Outlook, Microsoft documents exactly one repair path — through Installed apps → Advanced options — and one honest warning: Reset deletes the app's data, Repair does not. This page walks that path and marks the boundary of what these buttons can and cannot cure.
The new Outlook is a Microsoft Store app, so its repair controls live in Windows Settings, not inside Outlook:
Click Repair and let it finish. Repair checks and fixes the app's installation files without deleting its data — Microsoft states this explicitly on its support page. Your accounts stay signed in and the local synced copy stays in place. Open Outlook afterwards and test the folder that failed. A large share of app-side faults end right here.
Reset is the stronger medicine and the label is honest: Reset deletes the app's data on this device. That means the local cache and app settings are wiped and you will add your accounts again. It does not delete mail from the server — everything simply downloads again on first sync, which can take a while on a big mailbox or a slow connection. Do Reset only after Repair, and only when you know your account passwords.
Microsoft support agents also use a command version of the same reset. Open PowerShell and run:
Get-AppxPackage "Microsoft.OutlookForWindows" | Reset-AppxPackage
It performs the same reset as the Settings button — no deeper, no safer. Use whichever route you are comfortable with; there is no need to do both.
Be clear about the boundary: these buttons repair the new Outlook app only. If your error is the shared-PST conflict — the message names olk.exe while you are working in classic Outlook — resetting the new app does not remove the duplicate entry from classic Outlook's Data Files list, and the error will return. Do the conflict fix from the main guide first, then repair the app if the new Outlook still misbehaves on its own.
Watch the video for the conflict fix first — then use this page if the new app still needs its own repair.
▶️ Watch Full VideoIt deletes the app's local data on this PC — cache and settings. Your emails live on the mail server and download again when you sign back in. Nothing on the server is touched.
Always Repair first, because it keeps your data and fixes installation problems. Reset is the second step, only when Repair changes nothing.
Then you are looking at classic Outlook, which is part of Microsoft Office and is repaired differently — through the Office repair in the apps list, not these Store app buttons.