File cannot be loaded because the execution of scripts is disabled on this system error in PowerShell

When you try to run a Powershell script (PS1), you may get the following error:

File xyz.ps1 cannot be loaded because the execution of scripts is disabled on this system. Please see “get-help about_signing” for more details. At line:1 char:2

The reason for this error is the security setting on your pc that does not allow you to execute a script.  This is the so-called Execution Policy. By default, the Execution Policy is set to Restricted. This setting means that you may not run any PS1 script at all.

An overview of the policy levels:

Restricted: Individual cmdlets can run, but not saved Powershell scripts. This is the default setting.
AllSigned: Scripts can run, but must have a digital signature even if written on the local computer. Prompts you before running scripts from trusted publishers.
RemoteSigned: Scripts written on the local computer do not need a digital signature, but any script downloaded from outside (email, IM, Internet) must have a signature to execute. 
Unrestricted: Any script can run, but scripts downloaded from outside will run with a warning.

If you’re working on a desktop and just experimenting with PowerShell, the best is to set the policy-level to Unrestricted. This allows you do everything with annoying security boundaries. Just be careful not to run every script you download from the internet :)
If you’re working in a production environment and only want to run self-written scripts, the RemoteSigned level should be loosy enough.

To change the Execution Policy to Unrestricted, type the following command in Powershell

Set-ExecutionPolicy Unrestricted

To change the Execution Policy to RemoteSigned (to run your own scripts), type the following command in Powershell

Set-ExecutionPolicy RemoteSigned

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