I run a case with compiled UDF (user defined function). I save "case" and "data" file. Also there is "libudf" file at the same folders . When i read "case" and "data" file again, it works. However, after several days, it can not read "data" and "case" file as common when i want to read these "case" and "data" file again. The error information shows "open_udf_library: No such file or directory". Actually, the "libudf" file is still at same folder with "case" and "data" file. I did not do anything with these files. Do you know what is wrong with this problem? Thanks.

Are you running fluent in the same way as you did before? I think in some cases fluent looks in the "current" directory for files.