Burn bootloader to atmega328p-pu

Please do this:

  • File > Preferences > Show verbose output during: > compilation (uncheck) > upload (check) > OK
  • Tools > Burn Bootloader
  • After the process fails you'll see a button on the right side of the orange bar "Copy error messages". Click that button.
  • Paste the error messages in a reply here USING CODE TAGS (</> button on the toolbar).

Kinorter:
nope i don't use a cap

Sometimes you can get away without a 0.1 uF decoupling cap on the power lines but really you need one. This is a better tutorial: