TM4C1294KCPDT: Why we need to disable the interrupt of timer5?

Part Number:TM4C1294KCPDT

Dears:

We are using TM4C1294KCPDT, and we use some interrupts in code including timer0~4, I2C0~3, Mac, uart0, 1, 2, 7 etc.

In the below code the function of updateMCU() realises to update MCU on-chip FLASH's function as below picture:

However, we add a interrupt of timer5, the program will dead at function of updataMCU().

Then we add codes to disable  inferrupt of timer5 and the program is OK.

And we want to know why we use the below codes can not disable interrupt of timer5?

HWREG(NVIC_DIS0) = 0xffffffff;
HWREG(NVIC_DIS1) = 0xffffffff;

Best regards

Luck Wu