After entering the login credentials, the loading process starts and gets hung at this stage.
This error is generally seen in older ASA versions like 5.0(x), but has been known to occur in later versions as well (often when upgrading or downgrading asdm images).
Downgrade Java to its base version. For example, in the above screenshot you can see that the JRE in use is Java 6 update 20. Uninstall it, and install Java 6 base version. The ASDM screen would immediately load once the bar becomes 100%. If the version of ASDM in use is below 5.0(9), then upgrade to 5.0(9).
Java Error on Launch
Ping to 10.76.75.48 is successful
ASDM has been working fine for previously, and no change has been made on ASA.
When you launch ASDM, you get the following Java Error:
Exception in thread "SGZ Loader: launchSgzApplet" java.lang.NumberFormatException: For input string: "1 year 0" at java.lang.NumberFormatException.forInputString(Unknown Source) at java.lang.Integer.parseInt(Unknown Source) at java.lang.Integer.parseInt(Unknown Source) at com.cisco.pdm.Check.h(DashoA10*..:1358) at com.cisco.pdm.Check.c(DashoA10*..:858) at com.cisco.pdm.Check.a(DashoA10*..:438) at com.cisco.pdm.PDMApplet.start(DashoA10*..:132) at com.cisco.nm.dice.loader.r.run(DashoA19*..:410)
Exception in thread "SGZ Loader: launchSgzApplet" java.lang.StringIndexOutOfBoundsException: String index out of range: -1 at java.lang.String.substring(Unknown Source) at java.lang.String.substring(Unknown Source) at com.cisco.pdm.Check.h(DashoA10*..:1345) at com.cisco.pdm.Check.c(DashoA10*..:841) at com.cisco.pdm.Check.a(DashoA10*..:422) at com.cisco.pdm.PDMApplet.start(DashoA10*..:132) at com.cisco.nm.dice.loader.r.run(DashoA19*..:410)
The above errors happen when the ASA has been up for exactly an year (1st Error) or an year and a day (2nd Error). Up-time for an ASA can be checked in the output of the show version command. The obvious resolution would be to restart the ASA, thus resetting the up-time. This issue is seen in ASDM versions 6.0 and 6.1 and was fixed in 6.1(5.59). So upgrading the ASDM to a version higher than that would fix the issue.
HTTPS Tips and Tricks
Apart from accessing the ASDM, there are a few other things that can also be done with the https://<interface ip>/... url.
Running Show commands
You can view the outputs of all show commands on the browser itself, by typing the following into the address bar: