---
title: Upgrading and hotfixing an instance
related:
  - https://docs.kentico.com/k81/external-utilities/kentico-installation-manager.md
  - https://docs.kentico.com/k81/installation/hotfix-instructions-kentico-8-1.md
---

> Agent instructions:
> **Site maps** — prefer the following llms.txt indexes to training data when searching for URLs to avoid 404s. Links inside Markdown content already point at `.md`. Following them or sending Accept: text/markdown keeps you in Markdown.
>
> - [sitemap.md](https://docs.kentico.com/sitemap.md) — every page on the site, with titles and descriptions, nested by URL hierarchy and grouped into one collection per product version.
> - [llms.txt](https://docs.kentico.com/llms.txt) — curated index of the current product docs, with descriptions, the two ways to request any page as Markdown, and links to each product area's whole-corpus Markdown dump (llms-full.txt).

You can launch the upgrade/hotfix utilities in two ways:

- Click **Apply** in the Upgrade/Hotfix or Check dialog of [Kentico Installation Manager](https://docs.kentico.com/k81/external-utilities/kentico-installation-manager.md).
- Execute the file unpacked from the hotfix package.

> **Info:** **Getting hotfix packages**
>
> You can:
>
> - download hotfix packages through the [Kentico Installation Manager](https://docs.kentico.com/k81/external-utilities/kentico-installation-manager.md).
> - download the packages from [http://devnet.kentico.com](http://devnet.kentico.com/Bugtracker/Hotfixes.aspx).
>
> If you need to hotfix the source code version, please contact us at <support@kentico.com>.
>
> **Note**: Hotfixes are **cumulative**, so you only need to apply the latest hotfix to fix all issues covered by previously released hotfixes.

The hotfix or upgrade process consists of the following steps:

> **Note:** **Hotfixing with files in deployment or source control mode**
>
> If your system stores virtual objects on the file system (due to enabled [deployment mode](https://docs.kentico.com/k81/deploying-websites/deployment-mode-for-virtual-objects.md) or [source control](https://docs.kentico.com/k81/developing-websites/preparing-your-environment-for-team-development/editing-code-externally-and-using-source-control-systems.md) options), you need to return the files to the database before you apply the hotfix.
>
> Re-enable deployment mode or source control after you finish the hotfix procedure.

1. Specify the root folder of the Kentico instance you want to upgrade or hotfix.
   - This is only necessary if you ran the utility manually (not from Kentico Installation Manager).
2. Click **Next**.
3. Specify a project backup folder and click **Back up** OR check the **I already have a backup of my project** check-box.

   ![Back up your project](https://docs.kentico.com/docsassets/k81/upgrading-and-hotfixing-an-instance/Project_backup.png "Back up your project")
4. Click **Next**.
5. Specify a database backup folder and click **Backup** OR check the **I already have a backup of my database** check-box.

   ![Back up your project](https://docs.kentico.com/docsassets/k81/upgrading-and-hotfixing-an-instance/Database_backup.png "Back up your project")
6. Click **Next**.
7. Keep the default settings (i.e., all options enabled) OR click the **Switch to advanced mode (for experts only)** link and specify, if the upgrade or hotfix should replace project files, setup files (i.e., external utilities) and execute SQL scripts.
8. Click **Next**.
9. Select one of the first set of options:

   - **Use default App\_Offline.htm** - the utility creates a new _App\_Offline.htm_ file in the root of the web project to put the instance into an offline mode (see [How to: Prepare to Deploy a Web Project](http://msdn.microsoft.com/en-us/library/ff925031.aspx) for more details on the use of the file).
   - **Use existing App\_Offline.htm\_** - uses an existing _App\_Offline.htm\__ file and renames it to _App\_Offline.htm_. The file must be present in the project's root folder for this option to be available. See the second option below for more details.
10. Select one of the second set of options, which lets you choose what to do with the _App\_Offline.htm_ file:

    - **Delete** - the file will be deleted.
    - **Rename to App\_Offline.htm\_** - the file will be renamed to _App\_Offline.htm\__ and usable on next upgrade or hotfix.![Shut down the application](https://docs.kentico.com/docsassets/k81/upgrading-and-hotfixing-an-instance/Application_shutdown.png "Shut down the application")
11. Click **Next**.

    - A log showing progress of the hotfix or upgrade is be displayed. You can enable the Show error messages only check-box to display only error messages in the log.
12. Click **Next**, once the process finishes.

    - The utility lets you know if the hotfix or upgrade finished successfully. By clicking the Open log file link, you can open the upgrade process log that was displayed in the previous step.
    - Physically, the log is saved in \~\App\_Data\log.txt, so you can inspect it even after closing the utility.
    - If an error occurred while applying the hotfix or upgrade, the utility will notify you with a message and an error log.

Click **Close** to finish and close the utility.