'Refused to connect' error when trying to add app in SharePoint 2019

Question

Question:
When I am trying to add an app in SharePoint 2019, it says 'refused to connect'

Steps to reproduce error:

Open the app (K2 in my case) from site contents

Click on Add It button

Error shows up as "Refused to Connect"

Answer 1

Hi @shashank ,
I'm glad to hear you solve the problem ,if you have any issue about SharePoint, you are welcome to raise a ticket in this forum.

By the way, since the Microsoft Q&A community has a policy that "The question author cannot accept their own answer. They can only accept answers by others." and according to the scenario introduced here: Answering your own questions on Microsoft Q&A, I would make a brief summary of this thread:

['Refused to connect' error when trying to add app in SharePoint 2019]

Issue Symptom:
User is unable to add app in SharePoint 2019

Current status:
It's resolved by following Steps
First of all we need to install URL Rewrite IIS extension if it is not done yet. After that go to IIS Manager, select appropriate Sharepoint site and click URL Rewrite on the right side. Create new empty outbound rule like it is shown on the following picture:

You could click the "Accept Answer" button for this summary to close this thread, and this can make it easier for other community member's to see the useful information when reading this thread. Thanks for your understanding!

Answer 2

Enable Apps in Your SharePoint 2019 On-premise Farm
Step 1: Go to Central Administration. Open SharePoint 2019 Central Administration. From your SharePoint Server 2019 farm, open SharePoint 2019 Central Administration.
Step 2: Go to Store Settings. Navigate to Apps and Configure Store Settings. Start a trial.

Regards,
Peter

Answer 3

Hi @shashank ,

1. First, Please verify that the user account that is performing this procedure is a member of the site Owners group.
2. Disable and then re-enable the App Installation Service via Central Administration > Monitoring > Review job definitions > App Installation Service.
3. If you are still unable to add app, please try following powershell to install it param
   (
   [string]$Web = $(throw '- Need a SharePoint web site URL (e.g. "http://mysp15site/")'),
   [string]$Source = "ObjectModel"
   ) Write-Host -ForegroundColor White "----------------------------------"
   Write-Host -ForegroundColor White "| Corporate News App Installer |"
   Write-Host -ForegroundColor White "----------------------------------"
   Write-Host -ForegroundColor White "- " #Global vars
   $AppPackageName = "CorporateNewsApp.app"; #Loads powershell settings
   Write-Host -ForegroundColor White "- Load Powershell context.."
   $0 = $myInvocation.MyCommand.Definition
   $dp0 = [System.IO.Path]::GetDirectoryName($0) #Loads the SharePoint snapin
   Write-Host -ForegroundColor White "- Load SharePoint context.."
   $ver = $host | select version
   if ($ver.Version.Major -gt 1) {$host.Runspace.ThreadOptions = "ReuseThread"}
   if ((Get-PSSnapin "Microsoft.SharePoint.PowerShell" -ErrorAction SilentlyContinue) -eq $null) {
   Add-PSSnapin "Microsoft.SharePoint.PowerShell";
   }
   [void][System.Reflection.Assembly]::Load("Microsoft.SharePoint, Version=15.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c") #Imports the App package
   Write-Host -ForegroundColor White "- Import app package '$AppPackageName'..."
   $appPath = $dp0 + "" + $AppPackageName;
   if ($Source.Equals("ObjectModel", [System.StringComparison]::InvariantCultureIgnoreCase)) {
   $sourceApp = ([microsoft.sharepoint.administration.spappsource]::ObjectModel);
   }
   elseif ($Source.Equals("Marketplace", [System.StringComparison]::InvariantCultureIgnoreCase)) {
   $sourceApp = ([microsoft.sharepoint.administration.spappsource]::Marketplace);
   }
   elseif ($Source.Equals("CorporateCatalog", [System.StringComparison]::InvariantCultureIgnoreCase)) {
   $sourceApp = ([microsoft.sharepoint.administration.spappsource]::CorporateCatalog);
   }
   elseif ($Source.Equals("DeveloperSite", [System.StringComparison]::InvariantCultureIgnoreCase)) {
   $sourceApp = ([microsoft.sharepoint.administration.spappsource]::DeveloperSite);
   }
   elseif ($Source.Equals("RemoteObjectModel", [System.StringComparison]::InvariantCultureIgnoreCase)) {
   $sourceApp = ([microsoft.sharepoint.administration.spappsource]::RemoteObjectModel);
   } $spapp = Import-SPAppPackage -Path "$appPath" -Site $Web -Source $sourceApp -Confirm:$false -ErrorAction SilentlyContinue -ErrorVariable err;
   if ($err -or ($spapp -eq $null))
   {
   Write-Host -ForegroundColor Yellow "- An error occured during app import !"
   throw $err;
   }
   Write-Host -ForegroundColor White "- Package imported with success." #Installs the App
   Write-Host -ForegroundColor White "- Install the APP in web site..."
   $app = Install-SPApp -Web $Web -Identity $spapp -Confirm:$false -ErrorAction SilentlyContinue -ErrorVariable err;
   if ($err -or ($app -eq $null)) {
   Write-Host -ForegroundColor Yellow "- An error occured during app installation !"
   throw $err;
   }
   $AppName = $app.Title;
   Write-Host -ForegroundColor White "- App '$AppName' registered, please wait during installation..."
   $appInstance = Get-SPAppInstance -Web $Web | where-object {$.Title -eq $AppName};
   $counter = 1;
   $maximum = 150;
   $sleeptime = 2;
   Write-Host -ForegroundColor White "- Please wait..." -NoNewline;
   while (($appInstance.Status -eq ([Microsoft.SharePoint.Administration.SPAppInstanceStatus]::Installing)) -and ($counter -lt $maximum))
   {
   Write-Host -ForegroundColor White "." -NoNewline;
   sleep $sleeptime;
   $counter++;
   $appInstance = Get-SPAppInstance -Web $Web | where-object {$.Title -eq $AppName}
   }
   Write-Host -ForegroundColor White "."; if ($appInstance.Status -eq [Microsoft.SharePoint.Administration.SPAppInstanceStatus]::Installed) {
   Write-Host -ForegroundColor White "- The App was successfully installed.";
   $appUrl = $appInstance.AppWebFullUrl;
   Write-Host -ForegroundColor White "- The App is now available at '$appUrl'.";
   Write-Host -ForegroundColor White "- (Don't forget to add app host name in your host file if necessary...).";
   Write-Host -ForegroundColor White "- "
   }
   else {
   Write-Host -ForegroundColor Yellow "- An unknown error has occured during app installation. Read SharePoint log for more information.";
   }

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Answer 4

You can use this PS script to solve it:

add-pssnapin *

$f=get-spfarm

$f.AddGenericAllowedListValue("AllowIframeAppAuthorizePageDomains","yourdomain")

$f.update()