Is there any upper limit for number of versions a constant can have. We have c

No limit, but I recommend you don't do this. A high number of versions of a constant can increase the memory usage of your environment.

Instead you better use an external source like a database to store these values.

Thanks Eduardo, we are designing it to use the DB to store it. But was just curious to know the reason why it stopped working suddenly

I'll just confirm that there's no hard limit (other than 32-bit signed integer max, 2147483647), but that would be considered an excessive number of versions. I would expect operations related to versions would be slower than desired at that point.

Thanks Brian, I have updated to DB approach