i just updated from IAR Embedded Workbench V5.20 to V5.40 for a STm32 Cortex-M3. My software was operating correctly before I upgraded. Now after running the code for a few minutes, the software ends up in OS_Error() with a code of 254. I cannot find any documentation on the meaning of any of the OS_ERROR codes other than the OS_Error.c source code. Thanks Darren