A problem internal to GDB

I’m using mbed studio for debugging Nucleo-L476RG.

My debugging environment is
Mbed Studio ver : 1.4.3
Mbed OS ver :6.9.0

I got error about GDB when I was using debug mode.
The error message is show below.

A timing that I get the error is same every time.
I get the error after that I pushed “continue” after second break point .

Do you have any idea what is the cause of this error?