I then turned to attempting to make a bootable USB stick of OS X El Capitan from an image downloaded from Apple. I also tried Internet Recovery (Command+Option+R) but that gave exactly the same error (and would also only have installed OS X Mountain Lion). The detailed error log says “Chunk validation failed, retrying” about 1000 times and eventually gives up altogether.įurther investigation suggests this may be something to do with security certificates having expired and hence the machine not being able to download the necessary files from Apple’s servers, but it seems the error can appear for all sorts of reasons. After about 30 seconds, a window pops up saying “ Can’t download the additional components needed to install Mac OS X” and the installation gives up. I tried that with this machine, and upon hitting “Reinstall MacOS X” was greeted with a prompt telling me it would take -2,148,456,222 days and 8 hours (an uncaught buffer overflow, me thinks). Having recently fixed a busted MacBook Air I had learned a bit about Recovery Mode (hold Command+R whilst pushing the Power button and release a few seconds after the machine wakes up). Since there wasn’t much worth saving I wiped it and initiated recovery mode in order to re-install OS X (El Capitan). I was recently given a 2011 MacBook Pro that had been “well-loved” and was therefore a mess of missing applications, ghost files and generally slow-as-hell. How to make a bootable USB drive on Linux Mint (19.3) to allow you to install Mac OS X El Capitan on a MacBook with broken or corrupted recovery mode.

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