Google App Engine Development Server Throws The Following Error Whenever I Try To Run It

I'm trying to create a webservice using webapp2 and datastore in python. But whenever i try to run 'dev_appserver.py app.yaml' it throws me the following error ERROR 2017-10-11

Solution 1:

I see the same errors when trying to execute the dev_appserver.py from the Cloud SDK version 174.0.0.

However the dev_appserver.py from the standalone GAE SDK version 1.9.61 (theoretically the same being packed into the gcloud SDK 174.0.0) is running fine.

So one possible workaround to try would be to also install the standalone GAE SDK and run that dev_appserver.py instead.

Note: this is on linux, though, YMMV.

Related: What is the relationship between Google's App Engine SDK and Cloud SDK?

Solution 2:

The problem is fixed. Like @DanCornilescu said it's an environment issue. I deactivated the virtual environment. And It works fine with no issue.

Solution 3:

Solution for macOS. Maybe it works on Linux and Windows:

Find and remove folder:

appengine.None.<USER_NAME>

from the:

/var/folders

In may case:

/var/folders/6w/v0865mm96rj85dlwnr311bt00000gn/T/appengine.None.<USER_NAME>

Solution 4:

I'm refactoring some of my old golang applications and I ran into this problem. I'd oversimplified the spin-up of my web server not realizing this is a critical block of code:

// Critical to work on AppEngine
    port := os.Getenv("PORT")
    if port == "" {
        port = "8080"
        log.Printf("Defaulting to port %s", port)
    }
    log.Fatal(http.ListenAndServe(fmt.Sprintf(":%s", port), r))

Hope this helps.