> For the complete documentation index, see [llms.txt](https://docs.ecommerce.seb.ee/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.ecommerce.seb.ee/integration/web-plugins/opencart/installation.md).

# Installation

Install the SEB E-commerce Payment Gateway module for OpenCart

## Before you start

* OpenCart 4.x
* Your SEB E-commerce Payment Gateway credentials at hand (see [prerequisites](/integration/web-plugins.md))
* Admin panel access with extension-management permission
* Recommended: back up your store before installing any extension

## Install from the extension package

1. Download the OpenCart extension package.
2. In the admin panel, go to **Extensions → Installer**, select **Upload** and choose the downloaded file, then **Continue**.
3. In the installer list, select **Install** next to *SEB E-commerce Payment Gateway*.
4. Go to **Extensions → Extensions**, choose the extension type **Payments**, find *SEB E-commerce Payment Gateway* and select **Install** (green +).
5. **Required:** go to **System → Settings → Edit** your store → **Server** tab, set **Session Samesite Cookie** to **Lax** and save. OpenCart's default (*Strict*) logs customers out when they return from the payment page, shows them an error although they have paid, and delays the order update until the callback arrives.

![Extensions → Installer after upload, showing the uploaded extension in the installer list with the Install action.](https://1157570179-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FuBDtfypkI85zidcVwaDj%2Fuploads%2FsZfooADmKSNCQLqYsj1b%2Foc-installer-list.png?alt=media)

![Extensions → Installer after upload and after pressing the Install action, showing the installed extension.](https://1157570179-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FuBDtfypkI85zidcVwaDj%2Fuploads%2FV3Yq2hXEM9PI1CUWBszA%2Foc-installer-list-installed.png?alt=media)

![Extensions → Extensions → Payments, showing the installed extension row with Edit and Uninstall actions.](https://1157570179-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FuBDtfypkI85zidcVwaDj%2Fuploads%2FRILxR4SXxgbKP6PgoBHx%2Foc-payments-list.png?alt=media)

The extension needs no file edits and no environment-specific values beyond the credentials you enter in the admin. Continue with [Configuration](/integration/web-plugins/opencart/configuration.md).

## Uninstall

1. **Extensions → Extensions → Payments** → *SEB E-commerce Payment Gateway* → **Uninstall** (red −).
2. **Extensions → Installer** → select the extension → **Uninstall** to remove the files.

The extension's settings remain in the database after uninstalling from the Payments list; orders and their statuses are never removed. If you uninstall permanently, also delete the Callback URL registration in the Merchant Portal.

## Upgrade

Upload the new `.ocmod.zip` via **Extensions → Installer** and reinstall.


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