Hi! Can you explain how this error manifests? Can't find much info on it... Also, I don't want to update build until jam's voting period closes off.
You can change this in WebGL player settings.
Goto Edit -> Project Settings -> Player
A inspector window for player settings will be shown. In that select WebGL https://docs.unity3d.com/Manual/class-PlayerSettingsWebGL.html
And then check `Publishing Settings` section and uncheck Data caching.
Also here is forum thread discussing the same issue.