First check your Java. If you have a recent update, you should add your ASA(s) to the trusted sites for Java. Go via Java control Panel, Security and Edit the trusted site list to include https://<ASA address>.
We can look into other things once you've checked that.
If the devices are using the default self-signed certificate dynamically generated during boot-up they could have rebooted and thus changed their certificates (which would then have to be trusted anew by Java).
To avoid this, we generally try to use persistent certificates on the ASAs.
If that's the case for your, it's a good opportunity to generate a new certificate (using a 2048-but RSA key if you don't already have one) and bind it to the interface(s) you manage from.
BenefitsDocumentationPrerequisiteImage Download LinksLimitationsSupported PlatformsLicense RequirementsTopologyStep-By-Step ConfigurationConfigure Virtual ServiceActivate the virtual service and configure guest IPsConfiguring UTD (Service Plane)Configurin...
Login to the FXOS chassis manager.
Direct your browser to https://hostname/, and log-in using the user-name and password.
Go to Help > About and check the current version:
Check the current version availa...
We have configured the outside and inside Interface with official ipv6 adresses, set a default route on outside Interface to our router, we also have definied a rule , which also gets hits, to permit tcp from inside Interface to any6.
In Syslog I also se...