# 9. Common Installation and Execution Problems¶

Do you have a problem that is not documented below? No matter how trivial the problem might be, please raise an issue.

## 9.1. (The program hangs)¶

This is probably because a Bifrost pipeline was started with an infinite timeout, and some blocks are not ending themselves. Quit the program (by ctrl-\), and make sure every block in your pipeline is reading/writing to its rings as it should.

## 9.2. OSError: …./lib/libbifrost.so: undefined symbol: cudaFreeHost¶

At the make step, nvcc did not link cudaFreeHost into libbifrost.so. You should make sure that config.mk and user.mk are set up for your system, and that your nvcc compiler can compile other CUDA programs. If you are still having trouble, raise an issue.

## 9.3. OSError: Can’t find library with name libbifrost.so¶

This means that the bifrost Python wrapper can’t find your Bifrost installation. Whatever library folders it searches for Bifrost, you do not have the libbifrost.so file there. To fix this, type

echo $LD_LIBRARY_PATH at your command line. If none of these folders contain the Bifrost installation (which you specified in config.mk), you have found the problem. Perform export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/my/bifrost/installation,

where /my/bifrost/installation is the folder where you installed the Bifrost “lib” (in config.mk, this folder is given as INSTALL_LIB_DIR). This should add Bifrost to the wrapper’s search path.

## 9.4. OSError: libcudart.so.x.0: cannot open shared object file: No such file or directory¶

Similar to the above error. You need to add the CUDA libraries to the LD_LIBRARY_PATH search path.

For example, export LD_LIBRARY_PATH=\$LD_LIBRARY_PATH:/my/cuda/installation/lib64