---
title: Uploading files
---

> 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 upload files in Kentico either one by one or as multiple files. This can be useful if you need to upload a greater number of files at once, or if you need to perform the task quickly. Uploading multiple files at once is available for:

- **Media files** - files in [media libraries](https://docs.kentico.com/k8/managing-website-content/working-with-files/media-library-files.md) (e.g. **Media libraries -> Edit () _media library_ -> Files**).
- **Meta files** - files related to specified objects (e.g. [e-mail template](https://docs.kentico.com/k8/configuring-kentico/managing-e-mail-templates.md) attachments in **E-mail templates -> Edit () _e-mail template_ -> General**).
- [Document attachments](https://docs.kentico.com/k8/managing-website-content/working-with-files/document-attachments/attaching-files-to-documents.md) - files attached to documents (e.g. **Pages -> select _document_ -> Properties -> Attachments**).

## Enabling upload of multiple files

To enable upload of multiple files in the system, make sure:

- The value of the _**CMSUseSilverlightUploader**_ key is set to TRUE, or the key is not added to the _appSettings_ section of the _web.config_ file.

  ```html

  <add key="CMSUseSilverlightUploader" value="true" />

  ```
- The application has the write-to-disk [permission](https://docs.kentico.com/k8/installation/troubleshooting-installation-issues/disk-permission-problems.md) for the temporary files repository, i.e. for **\~\App\_Data\CMSTemp\MultiFileUploader**.
- Microsoft Silverlight is installed on your client computer.

## How it works

1. First you need to select one or more files from a given location.

![Selecting files](https://docs.kentico.com/docsassets/k8/uploading-files/selecting_files.png "Selecting files")

2. The files are downloaded as temporary files to a temporary repository (_App\_Data\CMSTemp\MultiFileUploader_). However, to upload the files successfully, during upload you need to avoid POST BACK on the current page.

3. When the upload is finished, the temporary files become the requested files:

![Media library](https://docs.kentico.com/docsassets/k8/uploading-files/media_library.png "Media library")

> **Note:** If you don't avoid POST BACK during the upload of multiple files or some other error occurs, the temporary files remain in the temporary repository.
>
> That's why there is the **Delete old temporary upload files** [scheduled task](https://docs.kentico.com/k8/configuring-kentico/scheduling-tasks.md) (configurable in the **Scheduled tasks** application), which deletes these temporary files, by default older than 24h. You can change this setting by changing the value of the **CMSDeleteTemporaryUploadFilesOlderThan** key (you need to manually add the key into the _web.config_ file of the current web project folder).