STM32F4 CAN2 TX mail boxes return full while using both CAN1 and CAN2 at 500KBPS

[RDodd.1]

I am trying to use both CAN1 and CAn2 with both 500KBPS . CAN1 transmits successfully . But for CAN2 TX mailboxes return full. 

Below is my CAN configurations file. Any help appreciated

[Imen.D]

Hello @RDodd.1​ and welcome to the Community :)

I advise you to have a look at the CAN example available within STM32CubeF4 MCU package:

\STM32Cube_FW_F4_V1.27.1\Projects\STM32469I_EVAL\Examples\CAN

Imen