Downloads use unusual compression format

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Downloads use unusual compression format

Post by lurch » Thu Jun 08, 2017 3:58 pm


I'm one of the developers on the Etcher project. It's getting quite popular now, so you may have heard of us ;) We're even mentioned in the Raspberry Pi image flashing instructions that you link to yourself.

Recently, in our chat room @htcnish reported that he was getting a strange error trying to flash your file using Etcher. (Etcher supports transparent decompression of archives, so there's no need to manually unpack them before writing)

I investigated the problem, and found out that the error is because you've compressed with a DEFLATE64 format, which the unzip library used by Etcher doesn't support.
So if you'd like to recompress your with a more standard compression format, then any users of Etcher will be able to flash your image onto their SD cards without getting a confusing error message. Alternatively, I guess you could update your instructions to say that (in contrast to most other zipfiles) your zipfile does need to be manually unpacked first, before being written with Etcher.
(just as a reminder, your instructions link to the Raspberry Pi instructions, which recommend Etcher and say that zipfiles don't need to be unzipped first)

And it's not just Etcher that this affects, @htcnish reported that even the standard unzipping utilities built into Mac OS X had problems unzipping this 'unusual format' zipfile, and he had to download a 3rd-party unarchiver program.

Hopefully I've managed to explain everything clearly, but if you have any further questions just ask...


Bertus Kruger
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Re: Downloads use unusual compression format

Post by Bertus Kruger » Thu Jun 15, 2017 6:49 pm

Hi Andrew,

Thanks for your post. I have had a look at Etcher in the past and it looks very clean. ;)

We will be releasing an updated version of the image soon and I will test with Etcher then.

The current image was done with Win32 Disk Imager and then compressed with Win10's built in zip utility.

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