Do you mean Firefox's plugin activation dialog redirects you, or Oracle's dialog redirects you? I'm assuming Oracle's.

Does your version of Java have a Control Panel section for adding trusted sites, or is yours too early for that? The documentation currently looks like this: https://www.java.com/en/download/faq/exception_sitelist.xml

Many thanks for your reply ... Sorry for the slow uptake. This was my next opportunity ...

The usual dialog asking whether to allow or block appears - but the Oracle page displaces it about 1 second later. I did manage to click on the Allow button in the dialog, despite its quick disappearance. It reacted, but it didn't help. The Oracle page displaced it anyway.

Oddly enough, when I try to open the Java control panel I get the error message from Explorer.exe : Application not found. This is the only machine in the company running this old version of Java - so I have no place else to look.

Javaw.exe is displayed as a process by the task manager. It is also listed in the Programs and Features control panel. Hmmm ...

The other odd thing is that, for another user, the process worked as expected, but the trusted app failed to run because the necessary encryption policy files are not installed. Unfortunately, he did not have permission to install them. I do. So I tried ... and can't even get Java to finish the connection.

It does seem like a catch-22, but how is Oracle intercepting the old dialog with its new page?? It's very strange. Maybe you have a mix of Java versions installed?

Yes - it's puzzling behavior, for sure. Just the one version installed, according to the "Programs" control panel. Also, it's the only version in the Java folder. Never seen anything quite like this on Firefox. Other browsers are quite ham-fisted about locking Java out - one of many things that keeps me appreciating Firefox.

I guess it's time to try re-installing this Java version again ... (tried it once, with no change.)

Thanks for your help ...