Programmer not responding, not in sync

I am not able to upload a sketch. The sketch worked fine a few days ago, and it works fine from the desktop IDE. It compiles but gets stuck at the "Flashing with command..." step and then eventually I get 10 attempts of:

avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0xf9

I've tried restarting the Create Agent plugin and restarting the browser. No go.
I also tried uploading a different sketch, no go.

Windows 10, Chrome v68. USB 2. Using an Arduino Mega 2560. I have tested two of them, same problem.

The only thing I can think of since I was successful a few days ago was I restarted my computer.

Easy steps first.

Remove anything that may also be connected to the board.

Clear your browser cache.

Are you selecting the correct COM port ? Windows 10 has a habit of hiding COM ports so use the "Show hidden devices" option in device manager.

Is it a clone or a true MEGA ?

When you select the board in CREATE are you also selecting the specific flavour of MEGA ?
If you can see the CHANGE option in the board drop down menu you should ensure you also selected 1280 or 2560 depending on the type of MEGA you have (1280 is older boards).

BTW the other topic was entirely different to this as it was specific to the CLOUD platform. We try not to mix topics as it can create confusion in answers.

That was easy! I am guessing the browser cache did it.
I also re-selected the board, flavor and port. The port was correct all along, and I don't know if the re-selecting jiggled something. So it was one of those steps at least. I had everything selected correctly, but perhaps doing it again re-connected it to the sketch. The quick message in the white pop-up did say "now connected to sketch..." which it hadn't done before.

FYI, the board is a Mega clone by Sunfounder, which has been pretty consistent.

Thanks for the advice!

While I have you, I was affected by an outage about a month ago, and just recently with this blank sketch problem that has gone around. I am about to use Arduino for a high school class and I wanted to use Create for the ease of no install, etc. But I can't have a glitch in the middle of class, or for a while day. Is Create stable or should I just fall back to the desktop IDE? I had high hopes for the Create idea.

PS- Looks like after I cleared my cookies I logged back in with my alternate account.

The user base for CREATE is huge and the lost sketch issue is a very very small glitch but one they take quite serious.
Arduino is also very involved with the EDU side of things with CREATE

We only see the problems here and not the many thousands of users without issue.
I use it a lot and have some fully deployed projects up there.
Most of the time I use it as a quick test bed for users with problems.

That said I have almost 800 sketches up there and have only recently been hit by the bug but it does tend to stick to a single sketch.

It never harms to have a second copy of a sketch that you may be working on as you yourself know how easy it is to swap over to a new board and sketch if you make a mistake in any way.

I think it is reliable enough at this point if you want my honest opinion.

I appreciate the response. Perhaps I'll have my students use Create and have the desktop IDE on hand just in case, plus do periodic back-ups.