Although I don't recommend it for general web browsing, you might try setting the general permission for the Java plugin to "Always Activate" in case the click-to-play feature is causing a problem.

Open the Add-ons page using either:

• Ctrl+Shift+a
• "3-bar" menu button (or Tools menu) > Add-ons

In the left column, click Plugins. On the right side, find Java SE and change "Ask to Activate" to "Always Activate".

Any difference?

Some pages may use the launcher plugin (I forget the exact name) in addition to the JRE. Do you notice any difference between your 45 and 52 in relation to that plugin?

Hello In both versions we have the Java plugin to "Always Activate", but this does not solve the problem in version 52.

I don't know how your switch does plugin detection, but a common method is to request a list of plugins from the browser. If you compare 45.9 and 52.4 on the following page, do the lists look the same, at least as far as Java goes?

https://www.jeffersonscher.com/res/plugins.html

we have the same plugins in both versions.

Do you mean on Firefox's internal page or how websites see them? I suggested using a web page to check that just in case there is a discrepancy.

If websites see the same Java plugin information, the switch may be using a function that became disallowed between Firefox 45 and Firefox 52. There are a wide range of changes that occurred over that time and I'm not sure how to determine exactly what the problem might be.

Does your switch manufacturer provide any information?

This site lists "highlights" of breaking changes, but isn't 100% comprehensive:

https://www.fxsitecompat.com/versions/52/ (and link for earlier versions)

Note that plugins other than Flash being disabled is for the standard release, not for ESR.