.ps1 cannot be loaded because the execution of scripts is disabled on this system

I run this code to execute PowerShell code from an ASP.NET application:

System.Management.Automation.Runspaces.Runspace runspace = System.Management.Automation.Runspaces.RunspaceFactory.CreateRunspace();
runspace.Open();
System.Management.Automation.Runspaces.Pipeline pipeline = runspace.CreatePipeline();
pipeline.Commands.AddScript(@"\\servername\path");

pipeline.Commands.Add("Out-String");

Collection<PSObject> results = pipeline.Invoke();

runspace.Close();

But I am getting an error:

.ps1 cannot be loaded because the execution of scripts is disabled on this system. Please see "get-help about_signing" for more details.

The same code runs fine from a command prompt or a windows (Windows Forms) application.

Your script is blocked from executing due to the execution policy.

You need to run PowerShell as administrator and set it on the client PC to Unrestricted. You can do that by calling Invoke with:

Set-ExecutionPolicy Unrestricted

There are certain scenarios in which you can follow the steps suggested in the other answers, verify that Execution Policy is set correctly, and still have your scripts fail. If this happens to you, you are probably on a 64-bit machine with both 32-bit and 64-bit versions of PowerShell, and the failure is happening on the version that doesn't have Execution Policy set. The setting does not apply to both versions, so you have to explicitly set it twice.

Look in your Windows directory for System32 and SysWOW64.

Repeat these steps for each directory:

1. Navigate to WindowsPowerShell\v1.0 and launch powershell.exe

2. Check the current setting for ExecutionPolicy:

   Get-ExecutionPolicy -List

3. Set the ExecutionPolicy for the level and scope you want, for example:

   Set-ExecutionPolicy -Scope LocalMachine Unrestricted

Note that you may need to run PowerShell as administrator depending on the scope you are trying to set the policy for.