Azure App Service Blank page after Deployment

Azure App Service Blank page after Deployment

Issue:

• After deployment when you try to access the function app/web app you get blank screen.
• You can see only blank page.
• You didn’t do anything for this and was not sure why this message was appearing.

Solution

I observed this message is set in <title> tag of html page which function app is responding when I call the URL.

   





Now to explain this issue in more details I would like to explain the concept of 
app_offline.htm file which is the part of your deployment process.

In an effort to make Kudu deployments avoid file locking issues, Kudu will now create a temporary app_offline.htm in the site's WWWROOT folder before starting the deployment. Kudu then takes care of deleting the file after deployment is complete.

The effect is that while deployment is happening, the app will be kept offline. In addition to avoiding file locking issues, this helps keep the site is a consistent state, by not serving any traffic while the contents of the site is only half-deployed.

Note: the file will only be created if an app_offline.htm file is not already present in the site's folder.

If you'd like to turn this behavior off, please add an SCM_CREATE_APP_OFFLINE App Setting to your app and set the value to 0. For more information about configurable settings, please check this page.

You can get more information on below URL,

https://github.com/Azure/app-service-announcements/issues/137

To get the final confirmation of this I tried to access this file from app and got the same response.(please check the URL in below screen shot)

That mean App has app_offline.htm file available in WWWROOT folder which was showing when calling the function app.

Ideally this file should have been deleted when your deployment is successful but I observed some unsuccessful deployment and that files was not deleted.

To resolve this,

• Delete the file and try again “or”
• Redeploy your application and make sure it is successful.

Feel free to share your feedback.

Other useful references,

Issue: Azure Functions: The Consumption pricing tier is not allowed in this resource group Solution : https://azureappservices.blogspot.com/2019/07/azure-functions-consumption-pricing.html

Issue: Azure function is throwing one of the following exception ·       Unable to retrieve Functions Keys ·       We are not able to retrieve the keys for function ·       The function runtime is unable to start. ·       Function host is not running. ·       Internal Server error. ·       Service Unavailable. Solution : https://azureappservices.blogspot.com/2019/07/azure-functions-unable-to-retrieve.html

Issue: Disable Azure functions https://azureappservices.blogspot.com/2019/07/how-to-disable-functions-in-azure.html

Function App | Unable to add function in Function App | Blank screen

Function App | Unable to add function in Function App | Blank screen

Issue:

• Sometimes you are not able to create a new function under your existing function app.
• Earlier You were able to add new function but now you are not able to add.
• You are able to see only a blank screen.

Analysis :

When You report these types of issue, Please collect the network trace immediately.

Please follow below steps to collect the network traces,

•    Hit F12 on your browser

•    Refresh browser (F5) - This will clear session caches

•    Reproduce the issue.

•    Export network trace as HAR file (Save all as HAR on Chrome/Edge/IE)

Once you have network trace then you can open it through Fiddler which will definitely give some information about some of the API failure.

In my case, I observed a lot of API failure for the /api/functions api

While investigating this API failure I observed lot of messages related to Network,

As the message says something about Network I quickly verified  the network setting but I was getting this issue in other networks also that means this issue is not pertaining to the network.

I then checked  Storage Account for this function.

https://docs.microsoft.com/en-us/azure/azure-functions/functions-create-function-app-portal#storage-account-requirements

I further checked and confirmed about unavailability of storage account.  

Somehow my storage account was deleted by someone which was causing that issue. I created a new function app and was able to add a new function successfully.

So whenever you face this issue please check the network trace and storage account availability.

Feel free to add/update anything if needed.