Bug Report

lto1.exe: internal compiler error: in lto_output_varpool_node, at lto-cgraph.c:624

Please submit a full bug report,

with preprocessed source if appropriate.

See http://gcc.gnu.org/bugs.html for instructions.

lto-wrapper.exe: fatal error: C:\Program Files (x86)\Arduino\hardware\tools\avr/bin/avr-gcc returned 1 exit status

compilation terminated.

c:/program files (x86)/arduino/hardware/tools/avr/bin/…/lib/gcc/avr/5.4.0/…/…/…/…/avr/bin/ld.exe: error: lto-wrapper failed

collect2.exe: error: ld returned 1 exit status

exit status 1
Error compiling for board Arduino/Genuino Uno.

Please advise if you need any additional information.
Thanks
Ron Besdansky

This bug is specific to the 5.4.0-atmel3.6.1-arduino2 version of avr-gcc used by Arduino AVR Boards 1.6.22 and newer. It has been reported here:

A workaround is described at the link above.

An alternate workaround:

  • Tools > Board > Boards Manager
  • Wait for downloads to finish.
  • When you move the mouse pointer over "Arduino AVR Boards", you will see a "Select version" dropdown menu appear. Select "1.6.21".
  • Click "Install".
  • Wait for installation to finish.
  • Click "Close".

Due to a bug, the alternate workaround doesn't work with Arduino IDE 1.8.6, but it will work with any other version of the Arduino IDE.

If you have File > Preferences > Check for updates on startup checked, the Arduino IDE may occasionally notify you that a new version of Arduino AVR Boards is available, you'll need to refrain from updating back to the Arduino AVR Boards 1.6.23 version, otherwise you'll be back to seeing the error again.