new software make old software not running


On a CC9P9215, I’m running a software using NET+OS 7.5.
When I buy a new CC9P9215, I can load my software version 1 and it is running fine. Software version 1 has been designed years ago.
Then I can load a newer version of my software that has been designed today. It is running fine.
But when I downgrade the CC9P9215 to my software version 1, it doesn’t run anymore. The CC9P9215 has got the orange and green LED blinking once.
And then if I load again the latest version of my software, then it runs fine.

Does anyone would have an idea of what can happen in the CC9P9215 with the latest software making impossible to run previous version of software that were running fine?

Thanks in advance for any help or suggestion.


This happen only on some CC9P9215.
Other CC9P9215 can run version 1 software after the downgrade without any problem.