timthumb returns 404 links after upgrading from Ubuntu 12.04-14.04

I recently upgraded my server to Ubuntu 14.04, and am in the process of upgrading it to 17.04. After muddling through Apache changes that were introduced in Apache 2.47, I was able to get my site serving again, but I think they must have changed something in their rewrite rules because despite a host of PHP warnings in my error log, there are no actual errors around my amplus theme. I’m not sure what’s going on here. I think it’s a configuration problem because the images were served correctly before I upgraded and if I copy the src from the image tag and load it in its own tab it shows up. I’d really appreciate help.

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