Error opening Office files in browser OOS.

Hi @Rui Pinto Ferreira ,

Welcome to Q&A forum!

There are many reasons for this, and certificate expiration is one of them. It is recommended that you follow the steps below for troubleshooting:

1. Check the Certificate Status on your servers

• Open the Microsoft Management Console (MMC) by typing mmc in the Run dialog (Windows key + R).
• Go to File > Add/Remove Snap-in.
• Select "Certificates" and click Add.
• Choose "Computer account" and click Next.
• Select "Local computer" and click Finish.
• Expand the Certificates node under "Personal" and look for the AppServerGeneratedSBCA certificate.
• Check its expiration date and validity.

2. Restart Relevant Services

Restart IIS Services on All SharePoint Servers and Office Online Server.

Restart SharePoint Services on All SharePoint Servers:**

• Open the Services console (services.msc).
• Restart relevant SharePoint services, such as "Microsoft SharePoint Foundation Web Application".

3. Check Permissions

Verify User Permissions in SharePoint:

• Go to the document library where the files are stored.
• Check the permissions for users who are experiencing issues.
• Ensure they have "View" permissions at a minimum for opening files in the browser.

4. Review Logs

1. On SharePoint Servers:

• Locate the ULS logs, typically found in C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\16\LOGS.
• Open the logs using a tool like ULS Viewer to filter and search for specific error messages related to the issue.

2. On Office Online Server:

• Review the event logs and any Office Online Server-specific logs for error messages that may provide more context.

5.Review Recent Changes

Identify any recent updates or changes made to the environment that could have impacted functionality.

Hope this can help.

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Hi @Rui Pinto Ferreira ,

Please try follow these general steps:

Request SSL Certificates using IIS:

On the first server in the Office Online Server farm, generate the certificate request. This step does not apply to other servers. It is recommended to use an actual SSL certificate issued either by a corporate domain certificate authority or a third-party authority.

https://www.sharepointdiary.com/2012/03/configuring-ssl-certificates-in-sharepoint-2010.html

non-official, just for reference.

Complete the Certificate Request using IIS:

When a response is returned by the CA, perform the necessary steps on the same machine used to create the certificate request sent to the Certificate Authority. This task is performed only once on the first Office Online Server.

Export SSL Certificate using IIS:

Once you have a complete SSL certificate, export the certificate to distribute to all OOS servers in the farm. This task is performed only once on the server where the certificate request was made and completed.

Import SSL Certificate using IIS:

After exporting the SSL certificate, import the certificate to install it on all other OOS server nodes. Copy the certificate to all OOS servers before continuing.

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