I am using Arduino 1.8.1 and arduino nano (mega 328p) and ftdi driver. In device manager it seems no problem, because it is detected as COM99. But it says a problem while uploading to the board as picture given. Please Helpp..
Looking at the error in the end about the invalid library, it seems a configuration problem and not a communication problem.
- Close and reopen the Arduino IDE (and check again)
- Remove the library and add it again (in the Manage library options in the menu), close/reopen the Arduino IDE (and check again)
- Reinstall the Arduino IDE (and check again)