Microsoft OneNote Online Certification Error

Hi John,

Thank you for sharing the details of your situation and for providing the certificate screenshot. 

As this is a user-to-user community forum, I do not have the ability to directly access or modify your account or service. However, I can provide guidance, recommend next steps, share applicable resources, and direct you to the appropriate support channels so the issue can be investigated further. 

Based on the information provided, the certificate being presented appears to be self-signed, as the Issued To and Issued By fields are both listed as word.cloud.microsoft. This differs from the certificate chain typically presented by Microsoft 365 services, which are normally issued by a trusted public Certificate Authority. 

Since the issue is occurring across multiple users and multiple devices, this suggests the problem may be related to a network component rather than an issue with individual workstations. 

Could you please perform the following checks? 

1. Test access to OneNote Online from an alternate network, such as a mobile hotspot, and confirm whether the issue persists. 
2. Test the following URL and confirm whether the same certificate error occurs: https://www.office.com 

If the issue only occurs on the corporate network, this would strongly indicate that the issue is related to a network security device, proxy, firewall, or SSL/TLS inspection process within the environment. In that case, I would recommend reaching out to your organization's IT or network security team and asking them to review the following: 

1/ Identify the certificate issuer 

• Open the page showing the certificate warning. 
• Select View Certificate. 
• Open the Certification Path tab. 
• Review the certificate chain and identify the issuer. 

If the issuer contains names such as Fortinet, Zscaler, Palo Alto, Sophos, Cisco Umbrella, Blue Coat, ProxySG, or another security vendor, this may indicate that HTTPS traffic is being intercepted and re-signed by a security appliance. 

2/ Check for SSL/TLS inspection 

Review any security solutions deployed within the environment, including: 

• Zscaler 
• FortiGate 
• Palo Alto 
• Sophos 
• Cisco Umbrella 
• Blue Coat / ProxySG 

Verify whether SSL/TLS inspection (HTTPS decryption) is enabled for Microsoft 365 traffic. 

3/ Review proxy configuration 

• On an affected workstation, open Internet Options > Connections > LAN Settings. 
• Check whether any of the following are configured: 
  • Automatic configuration script (PAC file) 
  • Explicit proxy server 
  • Transparent proxy 
• If a proxy is in use, temporarily bypass it for testing purposes if permitted by your organization's policy. 

Additionally, if needed, your IT team can also raise a support ticket with Microsoft Support through the Microsoft 365 Admin Center for deeper investigation. They have access to backend configurations and can perform a more in-depth investigation. At the very least, they can provide the most effective workaround to ensure your experience remains smooth and secure.      

• For detailed guidance on how to open a support ticket with Microsoft Support, please refer to: Get support - Microsoft 365 admin | Microsoft Learn  
• In case you do not know who is your IT admin, kindly refer to this article: How do I find my Microsoft 365 admin? - Microsoft Support  

I hope this information is helpful. Should you have any further questions or need additional assistance, please feel free to share them in the comment below. I'm very happy to help.  

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