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I have 2 separate environments, and some strange behaviour occurring in one environment that is not in the other. Specifically the error is related to the PHP:

Fatal error: Nesting level too deep - recursive dependency?

This only occurs on AWS, but not on our internal hosting which is an ESXi VM. Our attempts to synchronise PHP, PHP modules, Apache, Apache module versions and configurations have failed to eliminate this AWS-only error.

As a result we would now like to cast the net wider and look at dependencies and system wide configuration to try and further eliminate differences in the environment. I have been advised by co-workers at least on a conceptual level that there may be fingerprint tools for this very purpose.

Thanks for any suggestions.

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dpkg --get-selections combined with apt-cache policy will help; assuming both servers are using the same source mirrors, something like

{ for i in $( dpkg --get-selections | grep -v "deinstall" | cut -f1 ); do \
apt-cache policy $i; \
done } > $( cat /etc/hostname ).txt

might help to find specific package differences.

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