# Enforced Package Signature Verification

> After upgrading to Studio v2019.4 or above from an older version, some processes fail to execute. This is only applicable if package signature verification is enforced. Find out [how to sign a package](https://docs.uipath.com/studio/v2022.4/docs/signing-packages) and how the Robot [verifies a package signature](about-automation-projects-on-the-robot.md).

## Observed Behavior

After upgrading to Studio v2019.4 or above from an older version, some processes fail to execute. This is only applicable if package signature verification is enforced. Find out [how to sign a package](https://docs.uipath.com/studio/v2022.4/docs/signing-packages) and how the Robot [verifies a package signature](about-automation-projects-on-the-robot.md).

## Cause

Once the upgrade to Studio v2019.4 or above is done, the packages folder (`C:\Program Files (x86)\UiPath\Studio\Packages` in versions prior to 2021.4 or `C:\Program Files\UiPath\Studio\Packages` starting with version 2021.4) gets populated with signed activities packages, while also keeping the unsigned versions.

For example, the `Packages` folder contains both the `Microsoft.Rest.ClientRuntime.2.3.10.nupkg` (unsigned) and `Microsoft.Rest.ClientRuntime.2.3.12.nupkg` (signed) packages. When a process gets executed, the Robot uses the lowest applicable version to install the required package, which in our case is `Microsoft.Rest.ClientRuntime.2.3.10.nupkg` (unsigned). If package signature verification is enforced, then the process execution fails. Otherwise, the process is executed as expected.

## Solution

There are a couple of approaches to the situation:

1. Make sure all the packages used in your automation projects are signed.
2. Modify your processes so that they request the latest package version upon execution.

   :::note
   If signature verification is NOT enforced, processes created with Studio prior to v2019.4 are still executed, regardless if they are signed or not.
   :::