Connect-MgGraph fails with a TokenCache implementation error after module update

This looks like a module compatibility problem rather than an expired credential. The 2.40.0 Graph update appears to conflict with other PowerShell modules, especially when Exchange Online modules are loaded in the same session. Try installing and explicitly importing the previous Graph versions, such as 2.39.0, for the authentication and mail modules: `Install-Module -RequiredVersion 2.39.0 Microsoft.Graph.Authentication,Microsoft.Graph.Mail` followed by `Import-Module -RequiredVersion 2.39.0 ...`. Pinning the versions in the script can also prevent an automatic update from breaking it again.

Version 2.40.0 was released shortly before these failures appeared, so checking the module release notes or reporting it to the SDK maintainers would be worthwhile. As a temporary workaround, you can call the Graph REST endpoint directly with Invoke-RestMethod, although reverting to the last known-good SDK version is usually simpler for existing scripts.

Try running Connect-MgGraph by itself outside the full script. If it works in a clean PowerShell session but fails after the Exchange modules are imported, the assemblies are colliding. Splitting the work into separate scripts or sessions so each one loads only the required administration module can avoid the conflict. A clean session also helps confirm whether the issue is with authentication or with incompatible loaded assemblies.