Symptoms
After upgrading to 4.6.9 I get this error when trying to deploy a workflow. I'm not sure it has to do with 4.6.9 but I've never seen this error before "Invalid Archive Type"
Diagnoses
This error usually means a mismatch between components. If you are deploying from a client machine, make sure that the client tools are in the same version as the destination server. There might be also an issue with a component i.e SmartForms, Control Packs, SharePoint, that hasn't been upgraded to the last version.
Verify that in Control Panel - uninstall a Program - Programs that all the versions Match to the latest ones.
Resolution
Installing SmartForms resolved the "Invalid Archive Type".