Can't upload code: can't open device "/dev/ttyACM0"

Development Tools IDE 1.x
1

Hello, coders!!

I have got this problem where upon trying to upload my sketch to my Arduino Uno I get the following error:

An error occurred while uploading the sketch
avrdude: ser_open(): can't open device "/dev/ttyACM0": No such file or directory

I have investigated a bit and found out that my board is broken, as I have successfully uploaded my code to another Uno I had lying around.

Note: The Arduino guide for Linux has the following information for problems with uploading:

[i]It might happen that when you upload a sketch - after you have selected your board and the serial port -, you get an error Error opening serial port ... 
If you get this error, you need to set serial port permission.[/i]

[i]Open Terminal and type:
[/i]

ls -l /dev/ttyACM*

[i]you will get something like:[/i]

crw-rw---- 1 root dialout 188, 0 5 apr 23.01 ttyACM0

When I run that command I get the following error:

cannot access '/dev/ttyACM*': No such file or directory

I thought the board is fried, but the built-in leds are on when plugged into my PC, and the Arduino IDE still sees it on port ./dev/ttyUSB0, but without displaying "(Arduino Uno)"

Problem is the following:
The processor for the damaged board is Mega328P which is directly soldered onto the board, I can't just simply switch out the processor...

Is there any way I can resurrect the board?

2

UPDATE: Just after I posted this, I tried uploading again, without changing any setting, and it is now working as expected!!!

However I still want to know what caused the issue in the first place and what can I do to avoid getting into trouble again.