user53509: When trying to flash my sketch, I see many errors such as:
 ***failed;                                                                                                                            
 ***failed;                                                                                                                            
 ***failed;                                                                                                                            
avrdude: Error: butterfly programmer uses avr_write_page() but does not                                                                
provide a cmd() method.                                                                                                                                                                                           
 *** page 127 (addresses 0x7400 - 0x747f) failed to write

And also:
avrdude: error: programmer did not respond to command: set addr

How can I successfully flash my sketch?

user53509: After much frustration in trying things, I came across this forum post which advised:
sudo systemctl stop ModemManager.service

If this works, disable the service from starting next boot:
sudo systemctl disable ModemManager.service

It seems like setting ENV{ID_MM_DEVICE_IGNORE}="1" in a udev rule is insufficient. 

53509: <p>When trying to flash my sketch, I see many errors such as:</p>

<pre><code> ***failed;                                                                                                                            
 ***failed;                                                                                                                            
 ***failed;                                                                                                                            
avrdude: Error: butterfly programmer uses avr_write_page() but does not                                                                
provide a cmd() method.                                                                                                                                                                                           
 *** page 127 (addresses 0x7400 - 0x747f) failed to write
</code></pre>

<p>And also:</p>

<pre><code>avrdude: error: programmer did not respond to command: set addr
</code></pre>

<p>How can I successfully flash my sketch?</p>
 53509: <p>After much frustration in trying things, I came across <a href="https://forum.arduino.cc/index.php?topic=129647.msg3039571#msg3039571" rel="noreferrer">this forum post</a> which advised:</p>

<pre><code>sudo systemctl stop ModemManager.service
</code></pre>

<p>If this works, disable the service from starting next boot:</p>

<pre><code>sudo systemctl disable ModemManager.service
</code></pre>

<p>It seems like setting <code>ENV{ID_MM_DEVICE_IGNORE}="1"</code> in a <code>udev</code> rule is insufficient. </p>
