Error occurred in deployment step ‘Install SharePoint Add-in’: An instance of this App already exists at the specified location.

Recently I was trying to develop a SharePoint hosted add-in using visual studio 2015 and was trying to deploying to a SharePoint online developer site. But while deploying I got the below error, even I tried to deploy multiple times but every time it throws some error.

The error message comes as:
Skipping the uninstall step because the SharePoint Add-in is in an invalid state and cannot be uninstalled.
Error occurred in deployment step ‘Install SharePoint Add-in’: An instance of this App already exists at the specified location

Skipping the uninstall step because the SharePoint Add-in is in an invalid state and cannot be uninstalled
Skipping the uninstall step because the SharePoint Add-in is in an invalid state and cannot be uninstalled

Sometimes the below error also came:
Error occurred in deployment step ‘Install SharePoint Add-in:’ The remote server returned an error: (503) Server Unavailable.

Error occurred in deployment step Install SharePoint Add-in The remote server returned an error (503) Server Unavailable
Error occurred in deployment step Install SharePoint Add-in The remote server returned an error (503) Server Unavailable

Error occurred in deployment step ‘Install SharePoint Add-in’: An instance of this App already exists at the specified location

The errors were looking strange because I have not modified anything while developing the add-in, it was just a basic add-in without any customization. But still it was giving the same error, even I tried to redevelop the SharePoint hosted add-in but no success.

Sometimes the add-in did not uninstall properly then it will give an error like above. In those cases, you can remove the add-in from “Apps in Testing” in the developer site. You can select the add-in and then click on … and then click on REMOVE button like below:

error occurred in deployment step install app for sharepoint failed to install app for sharepoint
error occurred in deployment step install app for sharepoint failed to install app for sharepoint

Alternatively, you can also remove the add-in from the Site Contents page, Open the Site Contents page and then click on … and then click on Remove like below:

The remote server returned an error (503) Server Unavailable sharepoint online
The remote server returned an error (503) Server Unavailable sharepoint online

In my case it was different, Then I found out that there is a Service degradation in the SharePoint Online going on in the Office 365 tenant.

That information I found in the Office 365 Admin center Servce health section.

The below was the full message.

User impact: Admins may have been unable install or activate SharePoint add-ins or SharePoint Framework solutions.
Latest message: Title: Can’t install or activate SharePoint add-ins or SharePoint Framework solutions

User Impact: Admins may have been unable install or activate SharePoint add-ins or SharePoint Framework solutions.

Final status: We’ve completed deployment of the fix and confirmed that service has been restored.

Scope of impact: This issue could have potentially affected any admin attempting to install or activate SharePoint add-ins or SharePoint Framework solutions.

Start time: Monday, February 5, 2018, at 5:00 AM UTC

End time: Thursday, February 8, 2018, at 8:00 PM UTC

Preliminary root cause: A coding issue resulted in a problem in which admins were unable to install or activate SharePoint add-ins or SharePoint Framework solutions.

Next steps:
– We’re reviewing our update procedures to better identify similar issues during our development and testing cycles.

Admins may have been unable install or activate SharePoint add-ins or SharePoint Framework solutions
Admins may have been unable install or activate SharePoint add-ins or SharePoint Framework solutions

Once the Service restored, I am able to deploy the same SharePoint hosted add-in without changing anything.

Read some SharePoint Add-in tutorials below:

In this tutorial, we learned how to fix error, Error occurred in deployment step ‘Install SharePoint Add-in’: An instance of this App already exists at the specified location.

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