Unfortunately, the older versions of ASA don’t support the newer TLS versions… Further, the newer versions of Java disable support for the insecure versions of TLS, such as 1.0.

You’ll likely see an error like this:

This effectively means that you cannot use ASDM with updated Java on an old ASA…

To work around this there is a file located at:

C:\Program Files\Java\(Version of JRE)\lib\security

This folder may be in “Program Files” or “Program Files (x86)” depending on the version of Java installed.

Within this folder, there is a file named: java.security
Open this file, find the line “jdk.tls.disabledAlgorithms” and remove TLSv1

Another location to check, is within the local appdata folder

%USERPROFILE%\AppData\LocalLow\Sun\Java\Deployment

Here, there is a file named: deployment.properties
Open this file, add the line “deployment.security.TLSv1=true”
Then save the file.

After these change ASDM should be able to connect.