Office Settings & Configuration

How to Fix Expired Solver.xlam Digital Signature in Microsoft 365

Elise Williams Sep 25, 2026 869 views

Question details

Organizations using Microsoft 365 encounter an expired digital signature warning for the Solver.xlam add-in, which disrupts operations for many users.

How to Fix Expired Solver.xlam Digital Signature in Microsoft 365

Product: Microsoft 365
Device & OS: not provided
Scenario: Managing Office deployments across multiple users or countries where manual file replacement is not practical.
Observed behavior: The Solver.xlam add-in shows an expired digital signature. Repairing or reinstalling Office does not resolve the issue as the replacement file carries the same expired signature.

Before you start

Gather your affected file version, exact signature details, and current Microsoft 365 build number before proceeding with troubleshooting or contacting support.

Solution 1Recommended

Escalate to Microsoft Enterprise Support

Since local repairs do not update the expired certificate in the installer package, large organizations should contact enterprise support for a corrected build.

In managed environments with hundreds or thousands of users, manually replacing the add-in file is not a viable strategy. When you run an Office repair, the system merely reinstalls the files from the current deployment package, updating the file date but retaining the same expired certificate.

Collect deployment details

Note down your current Microsoft 365 build, the specific Solver.xlam file version, and the expired signature details from the file properties.

Open Microsoft 365 Admin Center

Submit a support ticket

Navigate to the Support section, create a new service request, and provide the collected deployment information, explicitly stating that repairing or reinstalling fails to update the expired certificate.

Escalate to Microsoft Enterprise Support

Solution 2

Check for Newer Office Updates

Microsoft occasionally patches expired add-in certificates in newer release builds.

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Switch to WPS Office for Seamless Spreadsheet Management

If Microsoft 365 add-in certification issues are disrupting your organization's workflow, consider WPS Office. It provides a lightweight, highly compatible alternative for handling complex spreadsheets without the overhead of enterprise-level certificate bugs.

Fully compatible with Microsoft Excel formats (.xlsx, .xls, .xlsm)Built-in data analysis tools without requiring complex add-in managementLightweight installation with zero complex enterprise deployment certificate issuesFamiliar user interface for immediate adoption and seamless migration

Frequently Asked Questions

Why does repairing Office not fix the expired Solver.xlam signature?

When you run an Office repair, it simply reinstalls the files from your current deployment package. If that package contains the version of Solver.xlam with the expired signature, it will replace it with the exact same expired file, only updating the modified date.

Can I manually replace the Solver.xlam file to fix the issue?

Yes, you can manually replace it with a newly signed version if you have one. However, this is highly impractical for enterprise environments with hundreds or thousands of users across multiple regions, which is why updating via admin policies or Microsoft support is recommended.

How do I check the digital signature of an Excel add-in?

Navigate to the add-in file location in your File Explorer (usually under the Office installation path in Program Files), right-click the file (such as Solver.xlam), select Properties, and click on the Digital Signatures tab to view the certificate details and expiration date.

Will reinstalling Microsoft 365 fix the expired certificate?

Reinstalling will only fix the issue if you are downloading a newer installation package where Microsoft has already updated the Solver add-in's certificate. Reinstalling from the same local deployment share will result in the same expired signature.

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