> For the complete documentation index, see [llms.txt](https://streamsmanager.gitbook.io/streams-manager/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://streamsmanager.gitbook.io/streams-manager/troubleshooting/plex/error-http-422-unprocessable-entity-when-inviting-a-user-or-processing-a-subscription.md).

# Error: HTTP 422 Unprocessable Entity when inviting a user or processing a subscription

This error can occur during the manual user invitation process or during checkout when a user selects a plan. It happens because Plex is unable to add the user to your Plex server.

Here are the most common reasons why this occurs and how to fix them:

* **User is already on the media server but un-synced**: The user may exist on your Plex server but isn't synced with Streams Manager. Navigate to the Users page and run a user sync to resolve this.
* **Out-of-date libraries**: If you recently modified your Plex servers or libraries and haven't synced those changes to Streams Manager, the invitation will fail because it references a library that has changed or no longer exists. Run a server sync in the Servers panel.
* **Changed Server Machine ID**: Ensure that your Plex server's machine ID has not changed. If it has, please refer to [this article](https://app.gitbook.com/o/ChJsgEF69mBSAf9zyAox/s/9BkTOk434ezw65fP9EYl/~/edit/~/changes/234/faq/how-to-change-price-of-a-plan) for instructions.
* **Server capacity reached**: Plex limits servers to 99 users (which includes friends, managed users, and home users). If you have hit this cap, no additional users can be added.
* **User is already in your Plex Home**: The invitation will fail if you attempt to invite a user who is already a member of your Plex Home.

> ⚠️ Important Note for PayPal Subscriptions: If this error occurs during a recurring PayPal checkout flow, you will need to resolve the issue manually. The PayPal subscription will likely have been successfully processed, but the user will not have been granted Plex access.