Unwanted received byte with UART+DMA

[Davood_Kesha]

Hello ST experts,
I have a weird experience with UART communication between two STM32G4 microcontrollers. MCU1 sends 10 bytes to MCU2 via UART. Both UARTS are configured with 9600 Baud rate with DMA in circular mode. The Problem arises when the MCU1 is turned on, it sends 11 bytes which the first byte is 0x00 in case I need only 10 bytes to be received. Can you help me in this issue?
Best,
Davood.

[TDK]

Put an external pullup resistor on the RX line so the line is idle high when the pin is not initialized.