inspect the configuration within your access-group, it seems you have an error there.
at first glance the versions are irrelevant, unless syntax has altered between versions.
-> correct and retry.
Google-AI gives the same answer as above
A "flexconfig error" is a Cisco Secure Firewall Management Center (FMC) error that most often occurs when you try to use a FlexConfig policy to apply commands that are either unsupported, blocked, or syntactically incorrect. Common causes include adding prohibited CLI commands, syntax mistakes in the FlexConfig object, or trying to configure features that have native equivalents in FMC policies. To resolve this, check for prohibited commands, preview and validate your FlexConfig object, verify the syntax against Cisco ASA documentation, and deploy it to a lab device first to test.
