I became an expert in a Filenet based system. After 5 years they wouldn't promote me even though I had filled the role of a tech lead for a year and senior dev for a year. The company decided to outsource my role, so I transitioned to a NeoXam team. I worked on the Neoxam based system for almost 2 years and they basically pushed me out by giving me a low bonus and a BS reason (they were cutting the program headcount 50% the next year). Now I'm starting all over on a new stack - AWS, Java, Python, and a ton of related technologies.