I upgraded a Nucleo-F767 project to mbed-os v5.12 and now receive random "LegacyAlign" errors and compiler 230 (syntax) errors with no reference to any code line. I have selected "Compile all" as suggested in other posts. Removing a good section of code allowed the program to compile and simply typing in a simple "" comment results in one or the other of the above errors. I have removed and re entered the comment and I seem to randomly get one of the above errors with no reason.

Revert only the mbed-os to 5.11.5 in the project and the project compiles without error and works as expected.

Tried another thing. Imported "mbed-os-example-blinky", made sure mbed-os was updated to 5.12. Initial compile works fine. Add comments and no problems. But if I add a simple one line assignment statement where the variables have not been declared you get:

Error: The build system did not finish successfully.

Error number is -230 and "In Folder" and "Location" are blank. The location of the compile error is not marked or higlighted.

Just update mbed-os-example-blinky to Mbed-os v5.12.1 and get same non-descriptive compiler error by just adding an undeclared variable (without compiles fine so not some platform issue):

The build system did not finish successfully. Error number: -230(help) Resource: <blank> In Folder: <blank> Location: <blank>

with no highlight/pointer in the code (see attached capture).