Can't send data to Nextion

My Nextion HMI could send data to the Arduino but The Arduino couldn’t send data to my Nextion. I could upload the HMI file via SD card but couldn’t upload the HMI file via Serial port. It was notification “connection failed Forced interrupt!”. All my pins are correct connected and I checked the continuity between Arduino UART with UART STM32 on the Nextion. I thought it was a hardware fault.
Sorry! My english is bad
My code:



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Support for Nextion on these fora is pretty much as follows:
You can follow the methods I set out in using Nextion displays with Arduino. My methods do not use the Nextion libraries, so while I am happy to offer help on using my methods I cannot offer anything very helpful for any Nextion library.
The original Nextion libraries are full of bugs. There is a link from my tutorial to some improved Nextion libraries created by Ray Livingston, I suggest those might be worth trying if you prefer to use a library.
There's also a separate Easy Nextion Library by Seithan, his methods are different to mine, choose which works best for you.
Beyond that the odd person occasionally offers a bit of help but not much.