SharePoint Add-In retirement in Microsoft 365

Hi Bert,

yesterday we have seen new comms from Microsoft in the M365 admin portal.
I was asking earlier, would the AppWeb data still be accessible via the API after 2026 April.
Does the text below imply that the AppWeb data will also be deleted and no longer accessible?

Microsoft is retiring SharePoint Add-Ins with a final retirement date set for April 2, 2026. Users are advised to migrate to SharePoint Framework (SPFx) and utilize the Microsoft 365 Assessment tool to prepare. Key dates include the halt of installations from the public marketplace starting July 1, 2024, and the removal of Add-Ins for existing tenants by April 2, 2026.

In the detail; it then says

Starting April 2nd, 2026, Microsoft will remove the ability use SharePoint Add-Ins for existing tenants.

Thanks

Hi Jansen,

If the AppUninstalled remote event is not notified in the new Add-in model, what alternative approach can be used to detect AppUninstalled events from a SharePoint site? Our provider-hosted application performs specific tasks when the app is installed or uninstalled based on remote event notifications.

In SPFx, how can we determine if an app has been installed or uninstalled from a site?

Hi BertJansen ,

We are trying to migrate the AppWeb data to the HostWeb because the AddIn model is being deprecated.

We want to use the SharePoint Migration API because of the large volume of data an AddIn instances we have on our clients.

We tried to do a basic test, regular site to regular site Migration using the Migration API and ran into problems.

When using SharePoint migration API with CreateSPAsyncReadJoband CreateMigrationJob we have an issue where CreateMigrationJob can’t parse the manifest that the CreateSPAsyncReadJob creates. It throws an error [System.Xml.Schema.XmlSchemaValidationException] [The 'Description' attribute is not declared.].

Question would be: is this is how it is intended to be used or does the manifest need to be somehow edited/modified before using it with CreateMigrationJob? If this is how it’s meant to be used then we would like guidance on resolving this bug/issue.

Target SharePoint environment

SharePoint Online

What SharePoint development model, framework, SDK or API is this about?

PnP.Core

Developer environment

Windows

Additional environment details

• PnP.Core 1.14.0
• PnP.Framework 1.17.0
• WindowsAzure.Storage 9.3.3

Bug / error description

1. Using CreateSPAsyncReadJob to create the migration package which works fine:

                           ClientResult<AsyncReadJobInfo> output = sourceContext.Site.CreateSPAsyncReadJob(

              listUrl,

               new AsyncReadOptions

               {

                  IncludeDirectDescendantsOnly = false,

                  IncludeSecurity = false,

                  IncludeExtendedMetadata = true,

               },

               null,

              manifestUrlReadWrite,

              reportQueueUrlReadAddUpdateProcess);

          sourceContext.ExecuteQuery();

1. Move the packages to root level of azure container.
2. Start migration job using CreateMigrationJob

          var migrationJobId = targetContext.Site.CreateMigrationJob(

             targetContext.Web.Id,

             sourceContainerUrlReadList,

             manifestUrlReadListWrite,

            reportQueueUrlReadAddUpdateProcess);

          targetContext.ExecuteQuery();

After the third step the migration job is started, after it runs for a while (processing security and other xml’s it fails on parsing the manifest.xml

[System.Xml.Schema.XmlSchemaValidationException] [The 'Description' attribute is not declared.]

Steps to reproduce

1. Create the manifest file using the CreateSPAsyncReadJob method
2. Copy and create snapshot for all xml files at the root of the container
3. Create the Import job using CreateMigrationJob method

Expected behavior

When import is started, the manifest file should be parsed without errors by the migration job, and migration of manifest content should be started.

Additional information

Migration is being done on a very simple list, just with one column “Title” and few items.

We tried using many different options, and using our Azure Storage, we could could not get it fully migrated end to end.

Ravi_Nalla : Like all other event receivers the AppInstalled, AppUpgraded and AppUninstalling depend on Azure ACS as authentication technology and that one is going away. It's recommended to integrate the action you'd normally trigger from these event receivers inside your SPFx application.

Hi Jansen,

In new Add-in model, if we install app(developed using SPFx) still we get RemoteEvent Notification for App Install/Unintsall/update in the form of webhook or any other way? In our existing Add-in (provider hosted) we get a notification in the form Remote Event when our App is added to SharePoint Site. Same facility availabl after current Add-in retirement? 

Smauglys : use bjansen@microsoft.com

BertJansen we would like to start a private conversation, but am getting an error while sending a message to you "You have reached the limit for number of private messages that you can send for now. Please try again later."
Could I contact you in some other way?

Thank you

Smauglys : when you uninstall the add-in the corresponding appweb is deleted as well. So the question remains on what will happen with the appwebs after Add-Ins have been retired and the Add-In was not uninstalled. We've not locked on the exact plans what will happen after April 2, 2026...can you elaborate more on why you still need access to the appwebs? If needed, feel free to start a private conversation to further discuss. 

Hi BertJansen ,

is there any official confirmation what will happen to the AppWeb data (lists/libraries and their list items, files) once the deadline of 2026 April 2nd passes?

Will the data be still reachable via the SharePoint API, or will the AppWeb data be deleted?

Example SharePoint hosted AppWeb url, with the app hash in the url of 254cae667cb57e, to the Documents library in our AppWeb of OurAddInAppWeb.

https://customerTenant-254cae667cb57e.sharepoint.com/sites/mySiteCollection/HR/LeaveRequest/OurAddInAppWeb/Documents

Could I get an official statement or a link to the documentation where it would state would the data be deleted or still reachable after the deadline.

Thank you

hello BertJansen,

In the original post, you say: "believe Microsoft 365 customers will be better served by modern SharePoint extensibility models". Can you please provide more details on how exactly modern models better service customers like myself who build enterprise data security solutions on synchronous RERs? 

I've already commented in Remote Event Receivers retirement update in SharePoint Online - Microsoft Community Hub, just joining AllanJuncherPedersen, M1980, MatthiasIwer, SteveBeauge and other participants here. Retiring a well-established proven solution without visible security and performance implications and replacing it with an inferior one which obviously failed to live up to the hype is a very questionable move which will definitely dent trust in Microsoft among enterprise IT professionals quite a bit.

I have no problem with learning new skills and methods, the issue here is that Microsoft are not providing any alternative to synchronous RERs at all.