Arduino mega code getting stop in between

I have a code which was perfectly working past 6 months on arduino mega and now the same code runs but stops in between.
I tried to debug it, by using Serial.println(“done Encrypition”) at various point and at one point its printing “done Enc” and getting stopped and than when i run it again its printing “done Enc” and getting stopped.
I have attached the screenshots, no changes were made in this version of code.
Is this problem with the board?

It sounds like you are running out of memory or reading/writing past the end of an array.

If only we could see your code ........

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