Message:
Agents are not available. Try again later.
Resolution:
“Agents are not available. Try again later.” message is shown on the Messaging for Web if the Omni-Channel flow didn’t use Route Work flow element to route the Messaging Session records.

reasonForNotRouting variable on the Salesforce Omni-Channel flow can be set to resolve this issue.
reasonForNotRouting will be returned only if the Omni-Channel Flow didn’t invoke Route Work action.
Message set to the reasonForNotRouting variable in the Omni-Channel flow will be shown on the Messaging Chat Widget.