I was getting this on my M5StickC-Plus, on the 10th/Oct/2022, with all the latest board/library updates.

I hope everyone else can find this thread!

For me the file I had to add those lines to was:

C:\Users[login name]\AppData\Local\Arduino15\packages\m5stack\hardware\esp32\2.0.5\boards.txt

For the record, I was getting this error with the M5StickC PLUS and your suggested edits to boards.txt fixed the problem. Thanks! Note that for whatever reason, I was not getting this error with an M5Atom.

Do you know how/when M5Stack does new releases that incorporates bug fixes such as these? Do we need to somehow notify them or do they regularly read the community forum? I'm aware of at least one library bug that someone has found a fix for in the forum. In that case, the user did a pull request on GitHub and the fix was pulled into the repository, but a new version of the library has not been released.

I don't think M5Stack are to blame, this was not a mandatory setting before.

After this update was installed I had the same problem with some of my M5Stack boards, but not all of them. A menu setting for erasing flash before upload or not must now be set. It seems that this menu setting must be sent to esptool, if this is not provided then esptool fails with the Address "{upload.erase_cmd}" must be a number error
There is a simple fix, if you can find your hidden arduino boards.txt file.
The path to the file will be different on Windows, Linux and OSX.
You need to add the following to boards.txt for ALL types of M5Stack/M5Stamp boards and then uploads should work again:

<board_name>.menu.EraseFlash.none=Disabled
<board_name>.menu.EraseFlash.none.upload.erase_cmd=
<board_name>.menu.EraseFlash.all=Enabled
<board_name>.menu.EraseFlash.all.upload.erase_cmd=-e

Replace <board_name> with the correct name for each type of board in the complete list. You can see what the name should be in the section for each M5Stack board.

After editing and saving boards.txt in the correct place, you need to restart the arduino IDE. You will then see in the Tools menu Erase All Flash Before Sketch Upload: Disabled/Enabled. This is the missing required setting for esptool.

Make a copy of your boards.txt before you make any edits so you can recover from any incorrect changes.

Good Luck!

other users: switching to the M5Stick-C (no "-plus") platform allowed me to upload new sketches to the device.

m5stick-c.menu.EraseFlash.none=Disabled
m5stick-c.menu.EraseFlash.none.upload.erase_cmd=
m5stick-c.menu.EraseFlash.all=Enabled
m5stick-c.menu.EraseFlash.all.upload.erase_cmd=-e

the sketch is very basic
'''
void setup() { }

void loop() { }
'''

the error is:
usage: esptool write_flash [-h] [--erase-all]
[--flash_freq {keep,40m,26m,20m,80m}]
[--flash_mode {keep,qio,qout,dio,dout}]
[--flash_size FLASH_SIZE]
[--spi-connection SPI_CONNECTION] [--no-progress]
[--verify] [--encrypt]
[--encrypt-files <address> <filename> [<address> <filename> ...]]
[--ignore-flash-encryption-efuse-setting]
[--compress | --no-compress]
<address> <filename> [<address> <filename> ...]
esptool write_flash: error: argument <address> <filename>: Address "{upload.erase_cmd}" must be a number
esptool write_flash: error: argument <address> <filename>: Address "{upload.erase_cmd}" must be a number

Please assist with getting my shiny new device to work.

Also the new OS X is a pain!