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1Clear out junk files and repair common Windows errors2Fix the driver behind crashes, sound loss and screen glitches3Repair Windows errors before they cause bigger problemsiTechGuides is reader-supported. When you buy through links on our site, we may earn an affiliate commission. As an Amazon Associate I earn from qualifying purchases. Learn more
First identify what failed: accepting an Outlook.com shared calendar, starting a Microsoft 365 app, or signing in to a desktop app. Microsoft documents different fixes for these cases; the HTTP 500 instructions apply specifically to accepting a shared calendar, not to every Microsoft 365 error with similar wording.
Identify the error before troubleshooting
Note the product, the action that triggered the message, and the complete error text or code. “Something went wrong” can refer to separate problems, so choose the section below that matches what you were doing.
- Accepting a shared calendar in Outlook.com and seeing HTTP 500: follow the calendar steps.
- Starting a Windows Microsoft 365 app: use the app startup steps.
- Signing in to a desktop app and seeing [1001]: use the sign-in steps.
- Having trouble accessing Outlook.com: check Microsoft’s service status.
HTTP 500 when accepting a shared Outlook.com calendar
Microsoft’s documented fix for this specific case is to select Accept again. If the HTTP 500 error appears more than once, contact Microsoft Support. This instruction is for accepting a shared calendar; it is not a general fix for every HTTP 500 error.
When the invitation is from Outlook.com to a Microsoft 365 business account
For this particular personal-to-business calendar-sharing scenario, Microsoft lists Outlook on the web, Outlook for iOS, or Outlook for Android as alternate ways to accept the invitation. If the recipient already selected Accept in Outlook 2016, Microsoft’s guidance says the sender should remove the existing permissions and send a new invitation. That workaround appears in an article dated May 2, 2017, so check Microsoft’s current page if its steps or interface no longer match: Outlook.com known issues.
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“Something went wrong” when a Microsoft 365 app will not start
If the error appears while launching an app rather than accepting a calendar, Microsoft’s separate startup guidance recommends this sequence:
- Wait a few minutes, then restart the device.
- Sign in again and restart the app.
- If the problem continues, repair the Microsoft 365 or Office installation using Windows Settings or Control Panel.
- If repair does not resolve it, uninstall and reinstall the installation using Microsoft’s instructions: Repair an Office application.
Microsoft notes that Online Repair can repair the entire suite even when only one app is affected. Follow the repair guidance for the Windows version and interface you have.
Desktop sign-in error [1001]
The [1001] code identifies a separate desktop-app sign-in issue, not the shared-calendar HTTP 500. Microsoft’s known-issues guidance describes scenarios involving security software that affects WAM (including AAD.BrokerPlugin) and user-profile management or roaming. The correct troubleshooting path depends on which scenario applies; see Microsoft’s known-issues guidance for Microsoft 365 sign-in errors.
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Microsoft lists rebooting as temporary relief and suggests Outlook on the web, Office web applications, or mobile apps as workarounds. For a business account, ask the tenant administrator to open a support ticket in the Microsoft 365 Admin Portal. Do not disable ADAL or WAM; Microsoft’s issue guidance links to advice that disabling them is not recommended.
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Check whether Outlook.com is experiencing a service issue
If Outlook.com itself is unavailable or behaving unexpectedly, check the Microsoft Office Online Services Service Health portal. Service status changes over time, so consult the portal for the current state rather than assuming an outage—or assuming there is none.
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