Migration Error from NIOS 11.2 to NIOS 12.1

[Altera_Forum]

After rebuilding my project after a long pause I discovered a building error in NIOS that seems to be related to the update from NIOS 11.2 to NIOS 12.1: 

 Description Resource Path Location Type Symbol 'EINVAL' could not be resolved alt_kill.c /converter_bsp/HAL/src line 103 Semantic Error Symbol 'ESRCH' could not be resolved alt_kill.c /converter_bsp/HAL/src line 111 Semantic Error Symbol 'SIGABRT' could not be resolved alt_kill.c /converter_bsp/HAL/src line 63 Semantic Error Symbol 'SIGALRM' could not be resolved alt_kill.c /converter_bsp/HAL/src line 64 Semantic Error Symbol 'SIGBUS' could not be resolved alt_kill.c /converter_bsp/HAL/src line 74 Semantic Error Symbol 'SIGCHLD' could not be resolved alt_kill.c /converter_bsp/HAL/src line 90 Semantic Error Symbol 'SIGFPE' could not be resolved alt_kill.c /converter_bsp/HAL/src line 65 Semantic Error Symbol 'SIGILL' could not be resolved alt_kill.c /converter_bsp/HAL/src line 66 Semantic Error Symbol 'SIGKILL' could not be resolved alt_kill.c /converter_bsp/HAL/src line 67 Semantic Error Symbol 'SIGPIPE' could not be resolved alt_kill.c /converter_bsp/HAL/src line 68 Semantic Error Symbol 'SIGPOLL' could not be resolved alt_kill.c /converter_bsp/HAL/src line 75 Semantic Error Symbol 'SIGPROF' could not be resolved alt_kill.c /converter_bsp/HAL/src line 76 Semantic Error Symbol 'SIGQUIT' could not be resolved alt_kill.c /converter_bsp/HAL/src line 69 Semantic Error Symbol 'SIGSEGV' could not be resolved alt_kill.c /converter_bsp/HAL/src line 70 Semantic Error Symbol 'SIGSYS' could not be resolved alt_kill.c /converter_bsp/HAL/src line 77 Semantic Error Symbol 'SIGTERM' could not be resolved alt_kill.c /converter_bsp/HAL/src line 71 Semantic Error Symbol 'SIGTRAP' could not be resolved alt_kill.c /converter_bsp/HAL/src line 78 Semantic Error Symbol 'SIGURG' could not be resolved alt_kill.c /converter_bsp/HAL/src line 91 Semantic Error Symbol 'SIGUSR1' could not be resolved alt_kill.c /converter_bsp/HAL/src line 72 Semantic Error Symbol 'SIGUSR2' could not be resolved alt_kill.c /converter_bsp/HAL/src line 73 Semantic Error Symbol 'SIGVTALRM' could not be resolved alt_kill.c /converter_bsp/HAL/src line 79 Semantic Error Symbol 'SIGXCPU' could not be resolved alt_kill.c /converter_bsp/HAL/src line 80 Semantic Error Symbol 'SIGXFSZ' could not be resolved alt_kill.c /converter_bsp/HAL/src line 81 Semantic Error Invalid project path: Include path not found (C:\APPS\Altera11\quartus\bin\cygwin\lib\gcc\i686-pc-cygwin\3.4.4\include). converter pathentry Path Entry Problem Invalid project path: Include path not found (C:\APPS\Altera11\quartus\bin\cygwin\lib\gcc\i686-pc-cygwin\3.4.4\include\c++). converter pathentry Path Entry Problem Invalid project path: Include path not found (C:\APPS\Altera11\quartus\bin\cygwin\lib\gcc\i686-pc-cygwin\3.4.4\include\c++\backward). converter pathentry Path Entry Problem Invalid project path: Include path not found (C:\APPS\Altera11\quartus\bin\cygwin\lib\gcc\i686-pc-cygwin\3.4.4\include\c++\i686-pc-cygwin). converter pathentry Path Entry Problem Invalid project path: Include path not found (C:\APPS\Altera11\quartus\bin\cygwin\usr\include). converter pathentry Path Entry Problem Invalid project path: Include path not found (C:\APPS\Altera11\quartus\bin\cygwin\usr\include\w32api). converter pathentry Path Entry Problem No break at the end of case alt_kill.c /converter_bsp/HAL/src line 89 Code Analysis Problem No break at the end of case alt_kill.c /converter_bsp/HAL/src line 103 Code Analysis Problem Unused declaration of function '_do_ctors' alt_main.c /converter_bsp/HAL/src line 54 Code Analysis Problem Unused declaration of function '_do_dtors' alt_main.c /converter_bsp/HAL/src line 55 Code Analysis Problem   The reason why I think that these errors are related to the software updates are that the invalid project paths are pointing to the previous location - ".../Altera11/...". (Why is still this previous path used?) All errors occur in the BSP (Board Support Package) which is automatically generated. Since this error did not occur previously, an include file (probably the standard library ?) seems to be missing. Before building, I ran the whole workflow process - generating in Qsys, building in Quartus and updating the BSP in NIOS.  All my attempts to solve this issue failed so far.

[Altera_Forum]

This issue is probably solved. 

I created a new "NIOS II Application and BSP from Template" using the updated NIOS II and then moved all previously created .c/.h files to the new created project.