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Topic: IDE fail "...rename 'core\core.a'; reason: File exists" or "reference to main" (Read 570 times) previous topic - next topic


I am having a lot of trouble with the IDE not compiling.  Windows 10, IDE 1.8.5, board is a Pro Micro 32U4.  Program is:
void setup() {
  // put your setup code here, to run once:
void loop() {
  // put your main code here, to run repeatedly:

If I change to UNO it compiles.  Change to Leonardo, it doesn't until suddenly it does.  Then I am ok for awhile, but then it doesn't.  It does not matter what is in the sketch - I am just using an empty sketch to provide a smoking gun to the problem.

c:/program files (x86)/arduino/hardware/tools/avr/bin/../lib/gcc/avr/4.9.2/../../../../avr/lib/avr5/crtatmega32u4.o:(.init9+0x0): undefined reference to `main'

collect2.exe: error: ld returned 1 exit status

exit status 1
Error compiling for board Arduino Leonardo.

Sometimes I get this message:

c:\programfiles(x86)\arduino\hardware\tools\avr\bin\../lib/gcc/avr/4.9.2/../../../../avr/bin/ar.exe: unable to rename 'core\core.a'; reason: File exists


It might be caused by your antivirus scanning newly created files. The solution would be to whitelist the problematic folders/programs.

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