Flash download tool error

[RouseA]

I was previously able to download firmware to an ESP32-C3-WROOM-02 using flash_download_tool_3.9.7.exe. Even this morning it was successful, creating an informative log file in the log folder.
However,for no apparent reason it stopped working. Each time I try it shows the attached

• I have a number of PCB assembiles with identical modules fitted and they all behave the same.

• I tried two different USB - Serial converters but it makes no difference. I do note, however, that the error message appears straight away. I connected a scope on the TXD and RXD lines and there is no activity so I don't believe the problem is with the serial connection.

• I tried it on two different laptops with the same result.

• I downloaded a new version of the Flash Download tool from https://www.espressif.com/en/support/do ... ther-tools and installed it in another directory. This includes flash_download_tool_3.9.9_R2.exe, but it gives the same result.

One thing that puzzles me is that although I select the ESP32-C3 device as Flash Download Tool starts, and the UART interface, the error message refers to ESP8266Loader_spi

I've run out of ideas....

[RouseA]

Further comment:
If I unplug the USB - RS232 interface the error message is the same, suggesting it isn't caused by the interface