A ctcatend condition was caused by trying to write to closed log files. When ctQTblockLogFiles is part of a ctQUIET request, the log files are actually closed at the system level. Even though ctQTblockLogFiles requires that ctQTblockAPI is in force and no transactions can be started, it was still possible for the quiet thread to cause log I/O to be attempted. The logic has been modified to correct this.