Hello，
I wrote a sourcefile when using version 0.12.1-dev, but an error occurred during runtime. But I don’t need a surface source, what should I do?
Thank you！
You would need to regenerate the source file using the same version of OpenMC that you are using now. Because the file format has changed between versions, if it was produced with an older version of OpenMC it may no longer work with newer versions as you are seeing from the above error message.