I ran apt update a couple times but still received the same error so I began looking into at /etc/apt/sources.list and /etc/apt/sources.list.d/ and noticed the following:
Code
Hit:16 http://www.deb-multimedia.org jessie InRelease
Hit:19 http://www.deb-multimedia.org jessie-backports InRelease
I replaced jessie with stretch and now I'm able to run apt update with no errors. I highly doubt it's related, but it certainly an odd coincidence.