An instance of this app is already exists at the specified location - when installing apps using powershell

Question

I am installing apps using powershell script and I want my script as rerunnable.

try
{
    $web.GetAppInstanceById()
    $appIoStream = New-Object IO.FileStream($AppFilePath,[System.IO.FileMode]::Open)
    $appInstance = $web.LoadAndInstallApp($appIoStream) | Out-Null
    $context.ExecuteQuery()
    Write-Host $appInstance.Id
}
catch
{
    $appIoStream.Dispose();
    Write-Host "Unable to Install App -" $AppName ": $_.Exception.Message" -foregroundcolor black -backgroundcolor Red
    return
}

Using this I can able to achieve the apps to be installed in the site collection.But when I am again running the powershell script I got an error that "an instance of this app is already exists at specified location". How can I handle this?

Answer 1

For that purpose I would recommend PnP-PowerShell module.

This module already contains a lot of helpful commands for managing SharePoint, including apps.

For example take a look at the apps cmdlets:

• Uninstall‑PnPAppInstance
• Get-PnPAppInstance
• Import-PnPAppPackage

With help of PnP you can solve your issue in a following way:

$app = Get-PnPAppInstance | ? {$_.Title -eq "<your app title here>"}
if($app -ne $null){
  Uninstall‑PnPAppInstance -Identity $app
}    
Import-PnPAppPackage -Path c:\files\my_app_file.app 

Only 5 lines of code.

UPD
Before running the script you need to connect to SharePoint using Connect-PnPOnline cmdlet. It asks for credentials, if you want to store credentials in your script (not or good approach and bad practice, but ok for development), you can instantiate a new site with PnP-Powershell using below code:

$username = "[email protected]"
$password = "pass"
$secstr = New-Object -TypeName System.Security.SecureString
$password.ToCharArray() | ForEach-Object {$secstr.AppendChar($_)}
$cred = new-object -typename System.Management.Automation.PSCredential -argumentlist $username, $secstr

Connect-PnPOnline -Url https://yoursite.sharepoint.com/sites/dev -Credentials $cred

Answer 2

You can try below options:

1. Change the ProductId in your appmanifest.xml in your VS project.
2. You need to remove the app from apps catalog or from site content and then upload it again.
3. Remove the app reference from recycle bin of SharePoint site.

After that you can run your powershell command and verify.