Enable Permissive Setting for HTML Pages

The case is mentioned here.

HTML Pages

Sometimes it is advantageous to use HTML pages of .html extension.
Example: Fully immersive pages with No SharePoint branding requirements

The Problem

Opening an .htm or .html page in SharePoint will actually download it.

download

Clicking on the file will lead to the download prompt.

prompt

The Solution

We need to change the following setting in Central Administration > Web Application > General Settings.

setting

Change the Browser File Handling to Permissive.

Permissive

Save changes by clicking the OK button.

Testing

Now click the .html file again and you will see the file get opened in browser.

browser

This confirms our setting was applied. Now we can create Fully Immersive Pages with .html extension.

Note:

Please note that the Browser Handling Setting is protecting the user from opening any Script content types. By default this option is set to strict mode. Please consult with your security team too before changing this setting.

References

http://bit.ly/1RxzPwH

Summary: In this post we have explored a common scenario while using HTML pages in SharePoint.