user47776: I have been working on several projects recently an made hundreds of uploads to several different boards.  I haven't had any issues to speak of.  Now I cannot upload. I have tried:

Disconnect all inputs and output from analog a digital ports - This is a board, nothing connected except USB.
Changing cables
Changing USB ports on my computer
Using a brand new out of the box Arduino Uno
Using example sketches, and even BareMinimum
Serial Loopback test - FAILED
Updating the driver with the one from the arduino folder
Using an unsigned driver
Manually setting the windows driver speed, parity, etc.
Uninstalling and re-installed Arduino IDE
Rolling back the board manager for AVR boards to 1.20 and 1.19
Change programmer to AVR ISP 

Here is the output:
Arduino: 1.8.5 (Windows 10), Board: "Arduino/Genuino Uno"

Sketch uses 444 bytes (1%) of program storage space. Maximum is 32256 bytes.
Global variables use 9 bytes (0%) of dynamic memory, leaving 2039 bytes for local variables. Maximum is 2048 bytes.
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0xc7
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 2 of 10: not in sync: resp=0xc7
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 3 of 10: not in sync: resp=0xc7
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 4 of 10: not in sync: resp=0xc7
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 5 of 10: not in sync: resp=0xc7
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 6 of 10: not in sync: resp=0xc7
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 7 of 10: not in sync: resp=0xc7
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 8 of 10: not in sync: resp=0xc7
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 9 of 10: not in sync: resp=0xc7
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0xc7
Problem uploading to board.  See http://www.arduino.cc/en/Guide/Troubleshooting#upload for suggestions.

This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.

Here is the verbose output:
Arduino: 1.8.5 (Windows 10), Board: "Arduino/Genuino Uno"

Sketch uses 444 bytes (1%) of program storage space. Maximum is 32256 bytes.
Global variables use 9 bytes (0%) of dynamic memory, leaving 2039 bytes for local variables. Maximum is 2048 bytes.
C:\Users\kanan\AppData\Local\Arduino15\packages\arduino\tools\avrdude\6.3.0-arduino9/bin/avrdude -CC:\Users\kanan\AppData\Local\Arduino15\packages\arduino\tools\avrdude\6.3.0-arduino9/etc/avrdude.conf -v -patmega328p -carduino -PCOM5 -b115200 -D -Uflash:w:C:\Users\kanan\AppData\Local\Temp\arduino_build_835373/BareMinimum.ino.hex:i 

avrdude: Version 6.3, compiled on Jan 17 2017 at 12:00:53
         Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
         Copyright (c) 2007-2014 Joerg Wunsch

         System wide configuration file is "C:\Users\kanan\AppData\Local\Arduino15\packages\arduino\tools\avrdude\6.3.0-arduino9/etc/avrdude.conf"

         Using Port                    : COM5
         Using Programmer              : arduino
         Overriding Baud Rate          : 115200
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0xd5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 2 of 10: not in sync: resp=0xd5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 3 of 10: not in sync: resp=0xd5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 4 of 10: not in sync: resp=0xd5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 5 of 10: not in sync: resp=0xd5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 6 of 10: not in sync: resp=0xd5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 7 of 10: not in sync: resp=0xd5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 8 of 10: not in sync: resp=0xd5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 9 of 10: not in sync: resp=0xd5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0xd5

avrdude done.  Thank you.

Problem uploading to board.  See http://www.arduino.cc/en/Guide/Troubleshooting#upload for suggestions.

This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.

I am not attempting to install the beta version of the arduino ide, but I am not betting this will work.
I feel like I have tried everything that is reasonable, and more than most people would think to try, what am I missing?
-------------  UPDATES --------------
I have now moved away from the arduino IDE and am working directly with avrdude.  Still no luck.  Running:
avrdude.exe -p m328p -c arduino -P COM6

fails.
I also tried it on my Fedora 27 box.  Here is dmesg output:
[349004.632101] usb 2-1.5: new full-speed USB device number 5 using ehci-pci
[349004.711497] usb 2-1.5: New USB device found, idVendor=1a86, idProduct=7523
[349004.711503] usb 2-1.5: New USB device strings: Mfr=0, Product=2, SerialNumber=0
[349004.711507] usb 2-1.5: Product: USB2.0-Serial
[349004.713405] ch341 2-1.5:1.0: ch341-uart converter detected
[349004.714652] usb 2-1.5: ch341-uart converter now attached to ttyUSB0

then I ran this:
$ dmesg | grep tty

And got this:
[    0.000000] console [tty0] enabled
[    0.781927] 00:06: ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is a 16550A
[   14.034377] usb 2-1.5: ch341-uart converter now attached to ttyUSB0

I then run this:
$ avrdude -p m328p -c arduino -P /dev/ttyS0

and get this:
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 2 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 3 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 4 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 5 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 6 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 7 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 8 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 9 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0x00

avrdude done.  Thank you.

At this point I also tried 
$ avrdude -p m328p -c arduino -P /dev/ttyUSB0

Same result.  At this point it seems to me I have a few fried arduinos.  They were fine yesterday, but today, they're toast.  Three computers, three cables, three arduinos, all the same result.
So, from here.  Has anyone heard of a bad cable frying an arduino?

user33045: Since your USB ports likely work for other things (like your keyboard) and you have tried several arduinos, cables etc, now try Knoppix - it has both Arduino IDE (not the most recent version) and avrdude.
https://unetbootin.github.io or
https://www.pendrivelinux.com/install-knoppix-6-to-a-usb-flash-drive-in-windows 
and
http://www.knopper.net/knoppix-mirrors/index-en.html
If it does not work, have a look through the boot log, or more quickly dmesg after plugging your arduino in and trying an upload.
Worth noting: the 328p target is not correct for mega, use e.g.: avrdude -vv -p atmega2560 -b115200 -c wiring -P COM3 or avrdude -vv -p atmega2560 -c wiring -P /dev/ttyUSB0. Omitting -b115200 should be no problem with the mega. Try this before torturing yourself further...
If you still get errors, and have not fiddled with clockspeed or anything else, it will be very strange indeed.

47776: <p>I have been working on several projects recently an made hundreds of uploads to several different boards.  I haven't had any issues to speak of.  Now I cannot upload. I have tried:</p>

<ul>
<li>Disconnect all inputs and output from analog a digital ports - This is a board, nothing connected except USB.</li>
<li>Changing cables</li>
<li>Changing USB ports on my computer</li>
<li>Using a brand new out of the box Arduino Uno</li>
<li>Using example sketches, and even BareMinimum</li>
<li>Serial Loopback test - FAILED</li>
<li>Updating the driver with the one from the arduino folder</li>
<li>Using an unsigned driver</li>
<li>Manually setting the windows driver speed, parity, etc.</li>
<li>Uninstalling and re-installed Arduino IDE</li>
<li>Rolling back the board manager for AVR boards to 1.20 and 1.19</li>
<li>Change programmer to AVR ISP </li>
</ul>

<p>Here is the output:</p>

<pre><code>Arduino: 1.8.5 (Windows 10), Board: "Arduino/Genuino Uno"

Sketch uses 444 bytes (1%) of program storage space. Maximum is 32256 bytes.
Global variables use 9 bytes (0%) of dynamic memory, leaving 2039 bytes for local variables. Maximum is 2048 bytes.
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0xc7
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 2 of 10: not in sync: resp=0xc7
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 3 of 10: not in sync: resp=0xc7
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 4 of 10: not in sync: resp=0xc7
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 5 of 10: not in sync: resp=0xc7
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 6 of 10: not in sync: resp=0xc7
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 7 of 10: not in sync: resp=0xc7
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 8 of 10: not in sync: resp=0xc7
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 9 of 10: not in sync: resp=0xc7
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0xc7
Problem uploading to board.  See http://www.arduino.cc/en/Guide/Troubleshooting#upload for suggestions.

This report would have more information with
"Show verbose output during compilation"
option enabled in File -&gt; Preferences.
</code></pre>

<p>Here is the verbose output:</p>

<pre><code>Arduino: 1.8.5 (Windows 10), Board: "Arduino/Genuino Uno"

Sketch uses 444 bytes (1%) of program storage space. Maximum is 32256 bytes.
Global variables use 9 bytes (0%) of dynamic memory, leaving 2039 bytes for local variables. Maximum is 2048 bytes.
C:\Users\kanan\AppData\Local\Arduino15\packages\arduino\tools\avrdude\6.3.0-arduino9/bin/avrdude -CC:\Users\kanan\AppData\Local\Arduino15\packages\arduino\tools\avrdude\6.3.0-arduino9/etc/avrdude.conf -v -patmega328p -carduino -PCOM5 -b115200 -D -Uflash:w:C:\Users\kanan\AppData\Local\Temp\arduino_build_835373/BareMinimum.ino.hex:i 

avrdude: Version 6.3, compiled on Jan 17 2017 at 12:00:53
         Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
         Copyright (c) 2007-2014 Joerg Wunsch

         System wide configuration file is "C:\Users\kanan\AppData\Local\Arduino15\packages\arduino\tools\avrdude\6.3.0-arduino9/etc/avrdude.conf"

         Using Port                    : COM5
         Using Programmer              : arduino
         Overriding Baud Rate          : 115200
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0xd5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 2 of 10: not in sync: resp=0xd5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 3 of 10: not in sync: resp=0xd5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 4 of 10: not in sync: resp=0xd5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 5 of 10: not in sync: resp=0xd5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 6 of 10: not in sync: resp=0xd5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 7 of 10: not in sync: resp=0xd5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 8 of 10: not in sync: resp=0xd5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 9 of 10: not in sync: resp=0xd5
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0xd5

avrdude done.  Thank you.

Problem uploading to board.  See http://www.arduino.cc/en/Guide/Troubleshooting#upload for suggestions.

This report would have more information with
"Show verbose output during compilation"
option enabled in File -&gt; Preferences.
</code></pre>

<p>I am not attempting to install the beta version of the arduino ide, but I am not betting this will work.</p>

<p>I feel like I have tried everything that is reasonable, and more than most people would think to try, what am I missing?</p>

<p>-------------  UPDATES --------------</p>

<p>I have now moved away from the arduino IDE and am working directly with avrdude.  Still no luck.  Running:</p>

<pre><code>avrdude.exe -p m328p -c arduino -P COM6
</code></pre>

<p>fails.</p>

<p>I also tried it on my Fedora 27 box.  Here is dmesg output:</p>

<pre><code>[349004.632101] usb 2-1.5: new full-speed USB device number 5 using ehci-pci
[349004.711497] usb 2-1.5: New USB device found, idVendor=1a86, idProduct=7523
[349004.711503] usb 2-1.5: New USB device strings: Mfr=0, Product=2, SerialNumber=0
[349004.711507] usb 2-1.5: Product: USB2.0-Serial
[349004.713405] ch341 2-1.5:1.0: ch341-uart converter detected
[349004.714652] usb 2-1.5: ch341-uart converter now attached to ttyUSB0
</code></pre>

<p>then I ran this:</p>

<pre><code>$ dmesg | grep tty
</code></pre>

<p>And got this:</p>

<pre><code>[    0.000000] console [tty0] enabled
[    0.781927] 00:06: ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is a 16550A
[   14.034377] usb 2-1.5: ch341-uart converter now attached to ttyUSB0
</code></pre>

<p>I then run this:</p>

<pre><code>$ avrdude -p m328p -c arduino -P /dev/ttyS0
</code></pre>

<p>and get this:</p>

<pre><code>avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 2 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 3 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 4 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 5 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 6 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 7 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 8 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 9 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0x00

avrdude done.  Thank you.
</code></pre>

<p>At this point I also tried </p>

<pre><code>$ avrdude -p m328p -c arduino -P /dev/ttyUSB0
</code></pre>

<p>Same result.  At this point it seems to me I have a few fried arduinos.  They were fine yesterday, but today, they're toast.  Three computers, three cables, three arduinos, all the same result.</p>

<p>So, from here.  Has anyone heard of a bad cable frying an arduino?</p>
 33045: <p>Since your USB ports likely work for other things (like your keyboard) and you have tried several arduinos, cables etc, now try Knoppix - it has both Arduino IDE (not the most recent version) and avrdude.
<a href="https://unetbootin.github.io" rel="nofollow noreferrer">https://unetbootin.github.io</a> or
<a href="https://www.pendrivelinux.com/install-knoppix-6-to-a-usb-flash-drive-in-windows" rel="nofollow noreferrer">https://www.pendrivelinux.com/install-knoppix-6-to-a-usb-flash-drive-in-windows</a> 
and
<a href="http://www.knopper.net/knoppix-mirrors/index-en.html" rel="nofollow noreferrer">http://www.knopper.net/knoppix-mirrors/index-en.html</a></p>

<p>If it does not work, have a look through the boot log, or more quickly <code>dmesg</code> after plugging your arduino in and trying an upload.</p>

<p>Worth noting: the 328p target is not correct for mega, use e.g.: <code>avrdude -vv -p atmega2560 -b115200 -c wiring -P COM3</code> or <code>avrdude -vv -p atmega2560 -c wiring -P /dev/ttyUSB0</code>. Omitting <code>-b115200</code> should be no problem with the mega. Try this before torturing yourself further...</p>

<p>If you still get errors, and have not fiddled with clockspeed or anything else, it will be very strange indeed.</p>
