Please follow the guide in yellow above and post the output after it has failed.

Ah thanks sorry I missed that. The compile is fine but the upload is failing. I have changed the title of the thread to make it easier to see.

This issue can sometimes show itself in either visual micro or the arduino ide. Sometimes related to cables and sometimes the usb driver. Please try to update from arduino 1.8.9 to the latest arduino ide 1.8.12. The toolchain has been updated and might resolve the issue.

stk500_getsync() attempt 1 of 10: not in sync: resp=0xe0

If you switch on the verbose upload on the uploader menu you will see the upload command. It is a one liner that can be pasted into a .bat or added to a cmd.exe command line. It should also fail.

I explained that the issue with avrdude can happen in either arduino or visual micro. It's a random long standing issue that fortnately isn't hit by many users. You will see many threads on the web about it.

I see you are using a custom board package that has its own avrdude. Please submit a verbose output from the arduino ide (file>preferences>verbose upload) so that we cn be sure the arduino ide uses the same copy of the toolchain.

This is the upload command from your output. Try it in cmd.exe and see if it works. Then try a second time.

ino5\bin\avrdude" duino5/etc/avrdude.conf" -v -V -patmega328p -carduino "-PCOM6" -b57600 -D sfdnlkjgfdshnegfdkh.ino.hex:i" 

The above command is how upload works so there isn't too much to get wrong.

I can also tell you it is not just about cables and board. An example from the past that a user found that adding just a little more code resolved the issue. In that case avrdude was hitting from magic internal limit that caused an issue.

Look forward to seeing the arduino output and hearing the results.

Thanks

nb: The arduino has the Uploader>Verify option on by default. It's possible that causing a verify makes the toolchain happier. I might be wrong but worth mentioning. You can enable "verify" on the vMicro>Uploader menu.