Unfortunately,your computer has another os installed

how to fix it plz help me what can i do to fix it

Have you used a different OS on your PC besides Windows?

i have not use any os besides window

What make/model of computer do you have?

You can run the installer in a special mode which ignores this error and continues to install Endless OS anyway:

  1. Find the Windows command prompt in the start menu, or you can do Start -> Run then type “cmd”
  2. Change to the folder you downloaded endless-installer.exe into. If your username is Example and the installer is in your Downloads folder, you might type cd c:\Users\Example\Downloads then press enter.
  3. Run the installer by typing endless-installer.exe /forcembr then press enter.
  4. The install should complete as usual.

After the install, if you can share with us the file “boottrack.img” you can find inside c:\endless (you will need to turn on options in Explorer to show hidden files, and show system files) then we can try and figure out why the installer thought you may have had another OS.

Thanks,
Rob

after install endless os …my hard drive data will be erased or not

i have dell inspiron 15 3000 series

Probably a bit late now, but this could be caused by running some of the incompatible software listed at https://github.com/pbatard/rufus/wiki/FAQ#Software

We could be a bit more sure if you could attach the EndlessInstaller[date] log file generated by the installer. Make sure you’ve downloaded the latest version from http://endlessos.com/ first.