If the Arduino IDE does not show the port or does not allow you to select the port, load a known to be working program (such as Example > Blink), start a download, and then double-click the board's reset button.

For the same advice plus extraneous information view this help page on the particular Feather, the 32u4 micro-controller board, which seems to suggest the use of a verbose download mode but that seems to be unnecessary.

If the Arduino IDE does not show the port or does not allow you to select the port, load a known to be working program (such as Example > Blink), start a download, and then double-click the board's reset button.

For the same advice plus extraneous information view this help page on the particular Feather, the 32u4 micro-controller board, which seems to suggest the use of a verbose download mode but that seems to be unnecessary because you can just try again if it failed. The verbose download mode is enabled in preferences. Even though it is unnecessary I eventually decided to always use the verbose download mode because it gives what appears, to me at least, more immediate and obvious feedback about success and failure.

If the Arduino IDE does not show the port or does not allow you to select the port, load a known to be working program (such as Example > Blink), start a download, and then double-click the board's reset button.

For the same advice plus extraneous information view this page which seems to suggest the use of a verbose download mode but that seems to be unnecessary.

If the Arduino IDE does not show the port or does not allow you to select the port, load a known to be working program (such as Example > Blink), start a download, and then double-click the board's reset button.

For the same advice plus extraneous information view this help page on the particular Feather, the 32u4 micro-controller board, which seems to suggest the use of a verbose download mode but that seems to be unnecessary.