Troubleshoot Outlook startup, mail delivery, search, attachments and profiles. Confirm whether you use classic or new Outlook before choosing a repair procedure.
◫Classic Outlook for WindowsResolved
Classic Outlook crashes when opening email sent by Viva Engage, Viva Insights, Yammer, Power Automate, or similar services
Known crash examples: Outlook 2024 LTSC 16.0.17932.20700 and 2021 LTSC 16.0.14334.20440. Check installation against the Office update history: the May 12, 2026 builds are 17932.20776 for LTSC 2024 and 14334.20670 for LTSC 2021.Event 1000
◫Classic Outlook for WindowsTroubleshooting guide
Outlook does not start, remains at Processing, or crashes while sending or receiving
Outlook for Microsoft 365 / Outlook 2024 / 2021 (Classic)
◫Classic Outlook for WindowsTroubleshooting guide
Mail connection, sending and receiving, or startup fails for one Outlook profile
Outlook for Microsoft 365 / Outlook 2024 / 2021 / 2019 / 2016 (features vary)
◫Classic Outlook for WindowsTroubleshooting guide
It says I'm working offline
Outlook for Microsoft 365 / 2024 / 2021 / 2019 / 2016（classic）Working Offline
◫Classic Outlook for WindowsTroubleshooting guide
No search results
Outlook for Microsoft 365 / 2024 / 2021 / 2019 / 2016（classic）Indexing Status
◫Classic Outlook for WindowsTroubleshooting guide
A message with a large attachment stays in Outbox
Classic Outlook for Windows (Microsoft 365 / Outlook 2024 / 2021) with the Send/Receive ribbon
◫Classic Outlook for WindowsTroubleshooting guide
Outlook window cannot open
Outlook for Microsoft 365/2024/2021Cannot start Microsoft Outlook
◫Classic OutlookTroubleshooting guide
PDF, Word, or Excel attachments will not preview
Classic Outlook for Microsoft 365 / 2024 / 2021 on Windows 11. New Outlook uses different menus and preview behavior.