Cannot find a proper pool for the tenant or user based on its ServiceInstance, Service Plan and TenantId.
The Provision pool overwrite rules has issue to cover this situation. Or we failed to read the topology file from Central Management Store.
Verify that Skype for Business Server is deployed correctly. use Get-csProvisionPoolAssignmentOverwriteRules -asXml to check the rules and tenant. And Use Get-CsProvisionServiceConfiguration to check current pool settings. Use Get-CsPool or Get-CsTopology cmdlet to retrieve the existing pool information and Publish-CsTopology to add a new pool.