I had a little fun sorting this out but here are the basic steps I took to get it working. This is using the upgraded version of Office 365 using SharePoint 2013.
- Create favicon.ico in GIMP
- Download ​SharePoint 2013 Designer and run
- Navigate to Site Assets
- Import favicon.ico
- Navigate to Master Pages
- I ended up editing both the .html and .master pages of the pages I am using.
- oslo.html
- oslo.master
- oslo-mobile.master
- seattle.master
- seattle.master
- Checked each file out
- Found the current favicon path and changed it to /siteassets/favicon.ico
- Check the files in
- I ended up editing both the .html and .master pages of the pages I am using.
- The favicon now showed when logged into the website but not for guest anonymous access. The trick was.
- Log in to Office 365 public website
- Click on the settings cog and select Site settings
- Under Look and Feel select design manager
- Select 3. Edit Master Pages
- My pages were in Draft Approval Status
- Click the three dots for the page
- Click the three dots on the pop up for the page
- Select to Publish the master version of the page.
- Log out and you should have your favicon working…I did.
Good luck