I have a newly converted forum that's facing an issue of intermittent undefined index errors related to styles and languages. It will persist for a few minutes and then disappear for hours. I'm looking for ideas on what might cause this.
Background: Forum converted over...
While trying to upgrade an existing XenForo 1.4.8 board I kept receiving Undefined use_tfa, there are no error stacks available but commenting out the content of the function _assertTfaRequirement under XenForo_ControllerPublic_Abstract fixed the issue for a time.