Like this post https://forums.balena.io/t/etcher-suddenly-not-working-on-imac-yosemity/4575 I have had the same error today despite no OS updates since well before the last time I used it.
Dismissing the message allowed me to write the USB stick (16GB SanDisk) with no errors 
Hey @Andyroo, thank you for letting us know of this issue.
Can you try updating to the latest version of Etcher? It should fix this issue.
Looks like that fixed the error 
May I ask what caused it?
To new icon is a bight bright to say the least and I’m not sure not the ‘project’ screen esp as the image I am creating has nothing to do with a Pi (its an x86 image),
@Andyroo, sorry for the delay.
That was a bug in the notification message that got fixed.
Regarding the project screen, it will change over time, we want to incentive people to build cool projects and learn more about the balena ecosystem.
Thanks for the feedback on the icon colors, I will notify the design team.
