The logfile_name log file could not be opened for writing. The log was not pruned and there will be no logging of events.
The log could not be opened for append. Therefore, there will be no logging done and the request to prune was not done.
Processing continues without logging and without pruning.
Determine why the log could not be opened. You may need to ensure that the file is not read-only, or ensure that a valid drive or partition is specified with the log file name.