Critical Issue
Description
Performing a clean build on a Nios II IDE project that contains a hardware accelerator can cause the next build to fail in the IDE, because the clean build erroneously deletes a file required by the C2H Compiler.
Resolution
Do not perform a clean build on projects that use hardware accelerators. If you have already performed a clean build, recompile with option Build software, generate SOPC Builder system, and run Quartus II compilation to regenerate the necessary files.