Xstore freezing at morning in register 2.

Xstore on Register 2 intermittently becomes unresponsive most mornings when attempting to open the register. When this occurs, Xstore freezes, and the store is unable to proceed until POS support intervenes to restart Xstore. After a restart, the register functions normally.
In log we could see the "Caused by: org.springframework.beans.factory.BeanExpressionException: Expression parsing failed; nested exception is org.springframework.expression.spel.SpelEvaluationException: EL1012E: Cannot index into a null value" this issue is happening only in Register 2. could you please give the suggestion or resolution for this issue.