[google-appengine] Re: A version of your app is using a deprecated version of Go. Please upgrade before October 1, 2019. Learn more

You may refer to the Go “Release History” page : “each major Go release is supported until there are two newer major releases. For example, Go 1.5 was supported until the Go 1.7 release, and Go 1.6 was supported until the Go 1.8 release”. Currently

[google-appengine] Re: A version of your app is using a deprecated version of Go. Please upgrade before October 1, 2019. Learn more

Based on the release notes feed, it was announced in June that Go 1.9 is deprecated and no *new* versions can be deployed after October 1. Existing versions, (e.g. GenericApp 1.5.0) will continue to run, but to release GenericApp 1.6.0 (or re-deploy 1.5.0) you'll have to do so using Go 1.11 or