OS X El Capitan installation failed – Copy of the installer can’t be verified

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OS X El Capitan installation failed – Copy of the installer can’t be verified

Hello,

I’m trying to install OS X El Capitan (10.11) on my iMac (Mid 2011) using a USB installer created via TransMac on Windows.

The installation process starts normally, but near the end, I get the error:

“This copy of the Install OS X El Capitan application can’t be verified. It may have been corrupted or tampered with during download.”

I already tried adjusting the system date in Terminal using the date command, for example:

date 101512002015

But the problem still persists.

My hard drive is formatted as Mac OS Extended (Journaled) with GUID Partition Map.
Internet Recovery doesn’t show any usable options except the globe symbol.

How can I fix this or get a verified version of the El Capitan installer that will pass the verification step?

Thanks in advance! 🙏

[Edited by Moderator]

iMac 21.5″, macOS 10.13

Posted on Oct 4, 2025 8:51 PM

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Answer 1

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MrHoffman

Community+ 2025

Level 10

144,009 points

Oct 4, 2025 9:23 PM in response to EmirBtnYLMZ

For assistance with this particular Windows path and this case, contact the people supporting TransMac.

Otherwise, you will want to use the Apple tools, which means a Mac to build a bootable installer, or use Recovery.

If the Mac has run macOS 10.12 or later (and its firmware updated), it should be able to get macOS 10.13 by booting Recovery, and macOS 10.13 which will have hassles, but fewer hassles than OS X 10.11 will have. Use Option-Command-R to boot Recovery for macOS 10.13.

If you really need OS X 10.11, install macOS 10.13, download macOS 10.11, unpack it, build an installer, boot thar, and wipe and load.

One of the Apple tools used here — read the whole article for the unpacking details for 10.11 — see the createinstallmedia tool:

Create a bootable installer for macOS - Apple Support

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