Restart recommended We detected that your session has unusually high memory - New Outlook

I am not in Europe, and I am also having this exact issue this morning. My Outlook desktop app for Windows 11 (new Outlook) updated itself and has repeatedly given this error since. I am in the USA on an enterprise Office 365 account.

Hello Martin,

Good day! Thank you for reaching out to the community.

It seems you're experiencing performance issues in New Outlook, with high memory usage leading to sluggishness and a restart prompt. I want to let you know that Microsoft is aware of a known issue affecting some users in Europe.

Known Issue Details

• Title: Some users in Europe may encounter performance issues with their Outlook client.
• User Impact: Users may notice Outlook using an increased amount of resources, causing the client to freeze or crash.
• Current Status: Microsoft is investigating telemetry logs and service diagnostics to identify the root cause and is developing a remediation plan. They have recycled components to reduce timeout errors, and further updates are expected soon.

If you believe your case may be related to this, feel free to update your issue accordingly.

Workaround

While Microsoft works on resolving this, switching to Classic Outlook has proven to be a temporary fix for many users. You can continue using this as a reliable option in the meantime.

The next update on this issue is expected by Thursday, October 10, 2024, at 1:30 PM UTC.

If you have any further questions or need assistance, please don't hesitate to reach out. We appreciate your patience during this time!

Thank you for your patience as Microsoft continues to work on improving the performance of New Outlook.

Please understand that our initial response may not always resolve the issue immediately. However, with your help and more detailed information, we can work together to find a solution.

Appreciate your patience and understanding and thank you for your time and cooperation. Have a great day!

Let me know how it goes! Thank you for being part of the Microsoft Community.

Sincerely,

Microsoft Community Moderator

I can confirm that I am also having this issue as well.

I rebooted once and the problem went away for a few minutes then I got an alert again. I ended up using OWA or/and mobile app.

I found Microsoft has this as an Active issue they're working on:

Issue ID MO907654:
Some users may encounter performance issues with their Outlook client

Issue ID: MO907654

Affected services: Exchange Online, Microsoft 365 suite

Status: Service degradation

Issue type: Incident

Start time: Oct 10, 2024, 4:59 AM EDT

User impact

Users may encounter performance issues with their Outlook client.

More info

Users may notice Outlook using an increased amount of system resources, causing the client to freeze or crash.

Scope of impact

Impact is specific to some users who are served through the affected infrastructure.

Current status

Oct 10, 2024, 11:27 AM EDT

Our investigation remains focused on isolating the source of a potential memory management issue which may be responsible for causing impact. We're working directly with some impacted organizations and are replicating the issue internally to generate additional data to further our efforts toward mitigation.

Next update by:

Thursday, October 10, 2024 at 12:30 PM EDT

I had the same issue. Even after a restart Outlook was using over 2.5 GB of memory and not responding. I went to Outlook Web Access, deleted a few thousand messages from folders that keep status updates, alerts and such and emptied my deleted items folder. I restarted Outlook again and now it's using about 450 MB. It looks like maybe it's trying to keep all messages in memory.