Hi @Hay, Suzanne (NRS),
Thank you for posting your question to Microsoft Q&A Forum.
Your Outlook contacts are not syncing to your iPhone after a Windows upgrade and phone rebuild. This typically happens because the sync connection between Outlook and iOS needs to be reconfigured after major changes.
I'd recommend you try the following steps to force sync your Outlook app on your device:
1/ Force quit and restart outlook app
- Swipe up from the bottom of your iPhone screen.
- Locate the Outlook app, then swipe it up to close.
- Relaunch Outlook from the home screen.
2/ Check account setup on iPhone
- Go to Settings > Mail > Accounts
- Ensure your Outlook account is added, and Contacts toggle is on.
3/ Clear Outlook app cache
- Go to Settings > Mail > Accounts. Find your work or school account and remove them.
- Open Outlook app > Tap your profile icon > Tap the gear icon (Settings).
- Account > Account Name
- Scroll down and select Reset Account (if available). This refreshes the sync profile.
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4/ Re-add the Email Account
- Open Outlook > Go to Settings > Accounts.
- Remove the affected email account.
- Re-add it using proper credentials (Microsoft 365, Exchange, or IMAP settings depending on your provider).
5/ Uninstall and Reinstall Outlook
- Long press the Outlook icon > Tap “Remove App”.
- Reinstall Outlook from the App Store. This ensures a clean install with updated settings.
6/ If the issue stays persist, to ensure you receive guidance tailored to your specific setup, I recommend reaching out your IT department directly and ask them to raise a ticket to Microsoft Support on your behalf.
A technical support engineer can initiate a remote session to guide you through the steps tailored to your tenant environment. During the session, they can verify backend configurations and run any necessary synchronization tools to resolve issues. If the issue requires further investigation, they will escalate the case to a specialized team for deeper analysis.

As community moderators, we kindly ask for your understanding that our access to internal development details is limited. Our primary role is to guide users toward the appropriate resources and support channels. While we may not have visibility into performing deeper backend analysis, we’ll continue doing our best to support you within the scope of our responsibilities.
I hope this information is helpful. If you have any questions or need further assistance, please feel free to share them in the comments on this post so I can continue to support you.
Thank you for your patience and understanding.
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