Changed from ColdFusion to C#. I was able to stretch minimal C# exposure during a contract into enough experience to convince someone to give me a full time gig where I was able to learn on the fly. I did pick up some bad habits that I had to unlearn as I gained more experience.

Twice so far.

Proprietary language to commonly used language - Got something on my CV that other future employers would appreciate more. Also was a chill job anyway. But I got bored.

Then I hopped jobs to another completely different commonly used language (not just different in syntax, but one that required a completely different way of thinking about things). I learned a lot, but project itself was way too stressful, so I quit at the end of my probationary period. Not a good outlook on my CV, but overall I can, without lying, say I pick up on new languages and frameworks very quickly and if I get a take-home assignment in a language I’ve never touched, I can still complete it in a reasonable time frame. So there’s some good out of it.

Both times also came with a significant salary increase so that’s also nice.

I’m withholding details about the languages because I might be too easy to identify given I’ve also mentioned my homeland in previous comments.

Sort of. I was a “language of the month” hobbyist. Then Visual Basic and Access with VBA came along and I could actually be productive enough to ditch my labour jobs in favour of a small freelance operation that generated comparable income, but was way more fun and much easier on my back and joints.

Go back to Java

Yes. Clisp to Java to Scala and to the Java finally. Every switch was to get more money. As a result in the end I got more money and more domain experience. Most switches were traumatic for a week and then it was back to normal.