Did you google the error? There’s at least one fairly large discussion of it here:
There may be mitigating steps you can do so I would keep googling until you exhaust your options.
It is late 2020, please use source control so that you can trivially attempt upgrades / migrations, comment out code or modules that will be expensive to properly upgrade, and at least see if the new version seem to pass a sniff check, and revert everything if they do not.