I tried many times, why did my Photoshop update fail?

There is no telling with the limited information you have provided.  Try using direct updates if you are not already doing so...

Direct Updates

https://www.adobe.com/downloads/updates/

cc updates: 
http://prodesigntools.com/adobe-cc-updates-direct-links-windows.html
http://prodesigntools.com/adobe-cc-updates-direct-links-mac.html

cc 2014 updates: 
http://prodesigntools.com/adobe-cc-2014-updates-links-windows.html
http://prodesigntools.com/adobe-cc-2014-updates-links-mac.html

cc 2015 updates:
http://prodesigntools.com/adobe-cc-2015-updates-links-windows.html
http://prodesigntools.com/adobe-cc-2015-updates-links-mac.html