Sometimes getting 521 error copying hex file to v2 microbit

[eanders-ms]

When a microbit project contains v2 blocks, copying the downloaded hex to device will often result in a 521 error.

FAIL.TXT

error: The hex file cannot be decoded. Checksum calculation failure occurred.
type: transient, user

Interestingly, this only seems to happen if the project contains v2 blocks. With only v1 blocks present, the copy succeeds reliably.

OS: Windows 11 Enterprise 22H2
Browser: Chrome 113

[eanders-ms]

Copies reliably to v2: https://makecode.microbit.org/_LaCAVuA5jEJm
Does not copy reliably to v2: https://makecode.microbit.org/_RyyXPYMFtL1V

[abchatra]

@jaustin @carlosperate have you seen this issue?

[martinwork]

@eanders-ms @abchatra

Related:
#5100
ARMmbed/DAPLink#1025
https://support.microbit.org/support/solutions/articles/19000145576-error-transferring-file-to-the-micro-bit-since-windows-update-in-february-2023

I saved the hex files for these projects and tested dragging each to V2.21, and the V1 one to V1.5, ten times. The error rate was about the same in all cases (3, 2, 4 fails).

[abchatra]

Duplicate of #5100