Can I upgrade Dolphin from 7.1 to 7.2.1 directly?

Can I ? And how?

Thanks!

• you need every version step by step to upgrade all versions down 
• From Dolphin 7.1.0 to 7.1.1. Released on March 14 2013
• From Dolphin 7.1.1 to 7.1.2. Released on May 9 2013
• From Dolphin 7.1.2 to 7.1.3. Released on June 5 2013
• From Dolphin 7.1.3 to 7.1.4. Released on July 31 2013
• From Dolphin 7.1.4 to 7.1.5. Released on January 19 2015
• From Dolphin 7.1.5 to 7.1.6. Released on May 28 2015
• From Dolphin 7.1.6 to 7.2.0. Released on September 21 2015
• From Dolphin 7.2.0 to 7.2.1. Released on October 19 2015

Additionally, make a backup before starting any work. And if you're doing a large upgrade run, take backups every few versions (or every version, if you have the patience). That way if one upgrade fails, you don't have to start over.

oh, my god, there are many steps :(

anyway, thanks!

That's what happens when you skip a year's worth of versions.