Problem in OTB groupstatus.aspx Sharepoint Online page and mobile browsers

In SPO there is one very useful OTB application layouts page groupstatus.aspx. Using this page we may redirect user to Notebook, Planner plan or Sharpeoint site associated with O365 group, e.g.

{siteUrl}/_layouts/15/groupstatus.aspx?target={target}

where {siteUrl} is url of the site associated with O365 group. And target may be "site", "notebook", "planner", etc. Full list may be found here: Generic URLs for all Office 365 Group connected workloads.
If we don't know url of the site associated with O365 group we may still use this page in context of the root tenant site and specify id of O365 group in additional query string parameter:

https://{tenant}.sharepoint.com/_layouts/15/groupstatus.aspx?target={target}&id={groupId}

 
In this case it will still redirect you to the requested target. And this is exactly how we use this page in TW - we open it in context of the root tenant site and provide target=site and id of the group in query string.
 
However at the same time Sharepoint has own redirection system for mobile devices: when you visit some Sharepoint site from mobile device it will redirect to special application layouts page optimized for mobile view \_layouts\Mobile\mblwpa.aspx (see Overview of Mobile Pages and the Redirection System). According to documentation this redirection for mobile devices is performed via http module (SPRequestModule). It means that in ASP.Net pipeline it will happen before request will come to groupstatus.aspx page. So when we redirect user to the root tenant site on mobile browser:

  https://{tenant}.sharepoint.com/_layouts/15/groupstatus.aspx?target={target}&id={groupId}

Sharepoint will just redirect user to mblwpa.aspx page in this root site

https://{tenant}.sharepoint.com/_layouts/15/mobile/mblwpa.aspx

and instead of seeing site associated with specified O365 group - user will see root tenant site. Will try to report this problem to MS using available communication channels. For now posted this problem on StackOverflow here.

How to enable Android App links in web-facing Sharepoint on-prem site

In previous article I showed how to enable universal links for iOS on Sharepoint on-prem site – see How to enable iOS universal links in web-facing Sharepoint on-prem site. In this post I will describe how to enable Android App links for web-facing Sharepoint on-prem site.

For Android App links the process is different. First of all we need to prepare special assetlinks.json file with predefined content:

[{
  "relation": ["delegate_permission/common.handle_all_urls"],
  "target": {
    "namespace": "...",
    "package_name": "...",
    "sha256_cert_fingerprints": ["..."]
  }
}]

I won’t describe here details about content of assetlinks.json file – you may find this information on Android documentation sites. Next step is to place assetlinks.json file into .well-known subfolder of the root folder of our site. On Sharepoint we can create this folder in site’s IIS folder C:\inetpub\wwwroot\wss\VirtualDirectories\{SiteName}.

After that we need to go to IIS manager > choose Sharepoint site > right click .well-known sub folder and click “Convert to Application”:

When .well-known subfolder is ready and configured in IIS manager we may copy assetlinks.json file there.

Now we need to make assetlinks.json file available for anonymous access (otherwise it won’t be available for Android infrastructure) and ensure that server adds Content-Type: "application/json" http header in response. In order to do that add the following web.config file to .well-known subfolder:

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <system.web>
      <authorization>
        <allow users="*" />
      </authorization>
    </system.web>
    <system.webServer>
      <staticContent>
        <clear />
        <mimeMap fileExtension=".json" mimeType="application/json" />
      </staticContent>
        <handlers>
            <remove name="JSONHandlerFactory" />
        </handlers>
    </system.webServer>
</configuration>

After that Android App links will be available on your web-facing Sharepoint on-prem site.

How to enable iOS universal links in web-facing Sharepoint on-prem site

Universal links allow to open mobile app when user clicks it inside the site. I.e. if user has appropriate mobile app it will be opened instead of regular browser page which will give better user experience on mobile devices. In this post I will show how to configure universal links for iOS in web-facing Sharepoint on-premise site. At the same time I won’t write about all steps like building mobile app itself, getting its app id, etc – please refer to appropriate resources related with mobile apps development for that.

In order to enable universal links for iOS on your web-facing Sharepoint on-prem site the following steps have to be done:

1. create AASA (Apple app site association) file. File name should be exactly “apple-app-site-association” without extension. It should contain data in json format with predefined structure (see below)
2. put it to the root folder of web-facing site
3. ensure that AASA file is available for anonymous users (robots) with Content-Type = “application/json”

This is how AASA file may look like:

{
  "applinks": {
    "apps": [],
    "details": [ { "appID": "{appId}", "paths": ["*"] } ]
  }
}

(use you app id instead of {appId} placeholder). When file is ready we need to copy it to the IIS folder of our Sharepoint site. Next step is to provide anonymous access and set correct content type. It can be done by modifying web.config of Sharepoint site – we need to add new location element here under configuration tag (usually in web.config of Sharepoint site there are many others location elements – so just put them together):

 <location path="apple-app-site-association">
    <system.web>
      <authorization>
        <allow users="*" />
      </authorization>
    </system.web>
    <system.webServer>
      <staticContent>
        <mimeMap fileExtension="." mimeType="application/json" />
      </staticContent>
    </system.webServer>
  </location>

It will make AASA file available for anonymous users and will set content type to “application/json”.

The last step is to verify that everything is configured properly. It can be done on AASA validator. Result should look like this:

At the end you should have universal links enabled for your web-facing Sharepoint on-prem site.

Update 2020-10-01: guide for enabling Android App links on Sharepoint site is available here: How to enable Android App links in web-facing Sharepoint on-prem site.