I am using a BGC controller version 3.1 "Tiny". One of its UART ports is connected to the STM32 microcontroller. The microcontroller itself implements a transparent bridge between UART port and TCP server. The TCP server can handle a maximum of one client at a time. On a new connection it disconnects the old client.

When trying to upgrade to a version 2.70b7_2 I get the following messages:

Pausing monitoring..
Signing request..
Downloading firmware...
Downloading firmware...
Writing data into file "C:\Program Files\SimpleBGC_GUI_2_71b7\firmware\simplebgc31_v2_70b8_0123299eef654f56ee.bin"...
Firmware is downloaded: 131052 bytes
Entering boot mode...
Waiting for bootloader to start...
Writing firmware...
Opening serial port WiFi (TCP/IP)..OK
Writing firmware to STM32 bootloader...
Reading firmware from file..OK, 131052 bytes
Connecting bootloader..OK
Disconnecting serial port WiFi (TCP/IP)..OK
Error upgrading firmware: Timeout waiting answer from bootloader!

I would like to ask what can cause this error.

Version of SimpleBGC GUI - v2.71b7_1.