Error message
In the message, %s marks a value that the engine fills in when it raises the error.
The story
You asked cron line to build a crontab entry, and the schedule was not shaped like one. A crontab schedule has exactly five fields, separated by spaces: minute, hour, day of the month, month, and day of the week. After those five, comes the command to run. Four fields is too few. Six is too many. If the engine just glued your text together, you would end up with a line that cron either rejects, or worse, misreads. A misread schedule is the nasty case: a job meant to run once a day could end up running every minute. So the engine refuses first, and tells you the schedule you gave and how many fields it actually found. Count them yourself. Say you wrote a schedule with the minute, the hour, and the day, and forgot the month and weekday. The message will say three. The fix: write all five fields, using a star for any field you do not care about. Then the line will be one that cron understands exactly as you meant.
Text from the Rush engine's error catalogue.