I continued to receive this same error after upgrading to the fixed releases. I had SSL decrypt known-key configured in firepower between the Internet and the ASA running VPN headend. This was breaking SSL secure server renegotiation, and displaying the same error mentioned in this bug for all clients running AnyConnect 4.8 and 4.9. Applicable to any version of ASA starting 9.13
Workaround or fix is to set 'do not decrypt' rule in firepower.
