Hi @SuzieQ and thanks for your help ,
I’ve just build the latest version of Heimdall myself (instead of using the version from the arch linux repo) and the same error occurs:
Uploading ODM
38%
ERROR: Failed to send file part packet!
ERROR: ODM upload failed!
Ending session…
ERROR: Failed to send end session packet!
Releasing device interface…
I am not sure what you mean by your last sentence, is it something I should check on the device itself?