OpenOCD doesn't open a gdb connection for a ST nucleo-h743zi board

I have successfully flashed a nucleo-h743zi board with a small app that blinks an LED and sends strings through the UART.

I'm now trying to connect to it with gdb, using OpenOCD v 0.12.0.

After building it, I execute this:

$./build/bin/openocd -f tcl/interface/stlink.cfg -c "transport select hla_swd" -f tcl/target/stm32h7x.cfg

And I obtain this:

Open On-Chip Debugger 0.12.0-rc2+dev-00989-g9501b263e (2022-12-15-15:37)
Licensed under GNU GPL v2
For bug reports, read
    http://openocd.org/doc/doxygen/bugs.html
hla_swd
Info : The selected transport took over low-level target control. The results might differ compared to plain JTAG/SWD
Info : Listening on port 6666 for tcl connections
Info : Listening on port 4444 for telnet connections
Info : clock speed 1800 kHz

(the command line returns after printing that)

I have tried as well

./build/bin/openocd -f ./build/share/openocd/scripts/board/st_nucleo_h743zi.cfg

and I obtain the same result.

I have double checked that the mentioned ports are not open with netstat -tulpn | grep LISTEN

As you can see, there is no gdb connection. I have tried telnet localhost 4444 as well, and I obtain:

Trying ::1...
Trying 127.0.0.1...
telnet: Unable to connect to remote host: Connection refused

What am I doing wrong?

The problem was that I had the STM32CubeProgrammer connected.