Fatal error: Undefined class constant 'E_PACKAGE_INVALID_APP_VERSION'

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I am getting this message, Fatal error: Undefined class constant 'E_PACKAGE_INVALID_APP_VERSION', when trying to download a theme. It happens on any theme. I have all of the files owned by www-data:www-data. I have php7.0 installed and I believe I have all php dependencies met (The installed had all check marks).

What am I doing wrong here?

On Ubuntu 16.04, PHP7.0

Concrete5 5.7