macOS El Capitan: can't verify installer fixed

Fri 01, Nov 2019 macos

Today I tried to install a freshly downloaded copy of macOS El Capitan on a Mac.

Shortly after starting the installation, the installer reported it could not verify itself and said that the image used to create the boot stick may be corrupted.

After opening up a Terminal and typing date it turned out, that the date was set to the year 2000. So the reason why it won't work, is that it can't verify the installer's certificate, because it's not valid before x and after y.

Here's how to fix it:

Hope it helps!

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