I'm having the ubuntu 15.04 iso image file. Can anybody tell me how can I upgrade my ubuntu 14.10 to 15.04. Thanks in advance...
2 Answers
You make a USB bootable or you put your image on a dvd. Then start your computer on the chosen support and make a classic install. It will ask you if you want to reinstall your system or if you want to upgrade it. Choose «upgrade to 15.04» then procede.

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Insert medium of installation (DVD, flash drive, etc)
Open dash (hit windows key) and type in "startup disk creator" and select that program.
The program should have already found the 15.04 iso but if you have more than one iso hit other and select it from the appropriate directory (where you downloaded it).
Follow the instructions from the program.
Once complete reboot PC making sure to go into boot options (different BIOS have different keys to hit, often it's F2 or F12) before Ubuntu starts to boot.
Select the medium that you installed the iso on and you should be on your way.

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