Customer raised a question about Upload Multiple Files button is disabled (Grey out) in SharePoint Online.
First thing that I test is to use IE, it works perfect. But my customer is using Chrome on it.
The root reason is SharePoint 2010 is using ActiveX Controls. To use it perfectly in Chrome, you need this tool.
IE Tab Extension
After it has been installed, you can easily navigate with IE TAB.
You will find it works perfectly.
However, in order to make it by default to browse your SharePoint site using IE TAB, you can set AutoURL on this.
Go to settings of IE TAB.
Add your SharePoint site URL to Auto URLs.
Therefore, every time that you access to the URL will automatically open with IE TAB.
Hope it helps those who are having headache on it.