Arduono setup and libraries

Hi, I get the following error message at compilation:

C:\Users\leif0\AppData\Local\Arduino15\packages\esp8266\tools\xtensa-lx106-elf-gcc\2.5.0-4-b40a506/bin/xtensa-lx106-elf-ar: unable to rename 'libraries\ESP8266WiFi\ESP8266WiFi.a'; reason: File exists

How to resolve?


This sort of error could be caused by your antivirus software. Try TEMPORARILY disabling your antivirus for a single compilation to see if the problem goes away, then turn the antivirus back on. If the problem doesn't occur with the antivirus off you will need to adjust the settings of your antivirus to whitelist the appropriate file, folder, or process so it doesn't interfere with compilation.

Thanks! I'll try it out. Leif

Hi again,

I deactivated my virus protection/fire wall and got this result trying to compile and upload my sketch:

Assembler messages: Fatal error: can't create sketch\WiFiTCPBlink.ino.cpp.o: Permission denied

Any ideas what I shall do?


Not all antivirus programs turn off fully from the AV user screens.
Which AV are you using ?

Also adding some additional hints that may apply.

Please READ THIS POST to help you get the best out of the forum.


These steps may also save you some unnecessary time and effort in the forum.


  • Check you have a COMMON GROUND where required.

  • Where possible use USB 2.0 ports or a USB 2.0 POWERED HUB to rule out USB 3.0 issues.

  • Try other computers where possible.

  • Try other USB leads where possible.

  • You may not have the correct driver installed. CH340/341 or CP2102

  • There may be a problem with the board check your wiring first.

  • Remove any items connected to pins 0 and 1.

  • Ensure you turn off any additional security / antivirus just to test.

  • There may be a problem with the PC try RESTARTING it.

  • You may be selecting the wrong COM port.

  • Avoid cloud/network based installations where possible OR ensure your Network/Cloud software is RUNNING.

  • Clear your browsers CACHE.

  • Close the IDE before using any other serial programs.

  • Preferably install IDE’s as ADMINISTRATOR or your OS equivalent
    Performing the above actions may help resolve your problem without further help.


Hi, I´m using McAfee but I don´t think my problem is related to the AV as I have used the same computer and software since more than a year without problem and now it just happens. The only thing that I can think of that has changed lately is that I have been running wifi-projects including the ESP8266. I have uninstalled the IDE, deleted libraries and tried again with the same outcome.

Good ideas on what to do please!