iCloud Drive keeps upgrading after IOS 10 install

Hi,

After installing IOS 10 on my iphone 6, my iCloud Drive shows it is upgrading (3 days now). I also cannot sign off from iCloud from the iphone ("failed to connect to iCloud" error message) and I cannot access iCloud Drive from Apple ID on a web browser (automatic bug report is sent to apple).

I am trying to sort this issue because I believe it is the source of my Mail app issue that cannot get any mail since the upgrade.

I couldn't care less about the iCloud Drive but I probably did something during the install to upgrade it (can't remember) so it is quite frustrating.

On my phone I so far and without change:

• hard reboot
• remove all my mail accounts, add some
• delete mail app, reinstall

I contacted apple support without improvement in my situation

Thanks for your help