A list of errors and warnings returned by the FeedValidator utility is listed below. Wiki users are encouraged to add descriptions and discussion under each message.

• File file name is not found (E1)
• File file name is empty (E2)
• Couldn't find a feed named feed name (E3)
• The feed named feed name had an unknown format: feeds should be either .zip files or directories. (E4)
• Files must be encoded in utf-8 and may not contain any null bytes (0x00). (E5)
• Missing column column name in file file name (E6)
• Missing value for column column name (E7)
• Invalid value value in field column name (E8)
• Duplicate ID value in column column name (E9)
• Invalid value value in field stop_desc. stop_desc should not be the same as stop_name (E10)
• Invalid value value in field route_short_name. Both route_short_name and route_long name are blank. (E10)
• Invalid value value in field route_desc. route_desc shouldn't be the same as route_short_name or route_long_name (E11)
• Invalid value value in field route_color. route_color should be a valid color description which consists of 6 hexadecimal characters representing the RGB values. Example: 44AA06 (E12)
• Invalid value value in field route_text_color. route_text_color should be a valid color description, which consists of 6 hexadecimal characters representing the RGB values. Example: 44AA06 (E13)
• Invalid value value in field departure_time. The departure time at this stop (%s) is before the arrival time (%s). This is often caused by problems in the feed exporter's time conversion (E14)
• Missing value for column departure_time. arrival_time and departure_time should either both be provided or both be left blank. It's OK to set them both to the same value. (E15)
• Missing value for column arrival_time. arrival_time and departure_time should either both be provided or both be left blank. It's OK to set them both to the same value. (E16)
• No time for first StopTime of trip_id "trip id" (E17)
• out of order stop time for stop_id=stop id trip_id=trip id (E18)
• The first stop_time in trip trip id is missing times. (E19)
• direction_id must be "0" or "1" (E20)
• Duplicate stop_sequence in trip_id (E21)
• No time for start of trip_id trip id (E22)
• No time for end of trip_id trip id (E23)
• Trip contains overlapping headway periods period 1 and period 2 (E24)
• can't have a nonzero transfer_duration for a fare that doesn't allow transfers! (E25)
• Each subsequent point in a shape should have a distance value that's at least as large as the previous ones. In this case, the previous distance was distance. (E26)
• Invalid value value in field shape_dist_traveled. This value should be a positive number. (E27)
• Invalid value value in field agency_timezone. "timezone" isn't a recognized time zone (E28)
• Invalid value value in field agency_id. The route with ID route id specifies agency_id agency id, which doesn't exist. (E29)
• A file must use a consistent line end. (E30)
• appears to be encoded in utf-16 (E31)
• contains a null in text text at byte byte number (E32)
• Unicode error (E33)
• In shape shape id, a negative sequence number number was found; sequence numbers should be 0 or higher. (E34)
• The sequence number number occurs more than once in shape shape ID. (E35)
• Invalid value value in field stop_sequence. This should be a number. (E36)
• Invalid value value in field stop_sequence. Sequence numbers should be 0 or higher. (E37)
• Invalid value value in field stop_id. This value wasn't defined in stops.txt (E38)
• Invalid value value in field trip_id. This value wasn't defined in trips.txt (E39)

• Unrecognized column column name in file file name. This might be a misspelled column name (capitalization matters!). Or it could be extra information (such as a proposed feed extension) that the validator doesn't know about yet. Extra information is fine; this warning is here to catch misspelled optional column names. (W1)
• stop name (ID stop id) isn't used in any trips (W2)
• This feed expired on date (W3)
• This feed will soon expire, on date (W4)
• Each line must end with CR LF or LF except for the last line of the file. This line ends with line ending example. (W5)
• Invalid value value in field stop_lat. Stop location too close to 0, 0 (W6)
• Invalid value value in field route_short_name. This route_short_name is relatively long, which probably means that it contains a place name. You should only use this field to hold a short code that riders use to identify a route. If this route doesn't have such a code, it's OK to leave this field empty. (W7)
• Invalid value value in field route_short_name. route_long_name shouldn't contain the route_short_name value, as both fields are often displayed side-by-side. (W8)
• Invalid value value in field route_short_name. route_long_name shouldn't be the same the route_short_name value, as both fields are often displayed side-by-side. It's OK to omit either the short or long name (but not both). (W9)
• Invalid value value in field route_color. The route_text_color and route_color should be set to contrasting colors, as they are used as the text and background color (respectively) for displaying route names. When left blank, route_text_color defaults to 000000 (black) and route_color defaults to FFFFFF (white). A common source of issues here is setting route_color to a dark color, while leaving route_text_color set to black. In this case, route_text_color should be set to a lighter color like FFFFFF to ensure a legible contrast between the two. (W10) You may find a color picker tool such as http://snook.ca/technical/colour_contrast/colour.html handy.
• This stop time has a pickup_type and drop_off_type of 1, indicating that riders can't get on or off here. Since it doesn't define a timepoint either, this entry serves no purpose and should be excluded from the trip. (W11)
• Point location too close to 0, 0, which means that it's probably an incorrect location. (W12)
• The shape with shape_id "shape id" contains no points. (W13)
• Service period with service_id service id doesn't have service on any days of the week. (W14)
• This feed has no effective service dates! (W15)
• The stops stop name 1 (ID stop id 1) and stop name 2 (ID stop id 2) are so close together that they probably represent the same location. (W16)
• The same combination of route_short_name and route_long_name shouldn't be used for more than one route, as it is for the for the two routes with IDs route ID 1 and route ID 2. (W17)
• The trip with the trip_id "trip id" doesn't have any stop times defined. (W18)
• The trip with the trip_id "trip id" only has one stop on it; it should have at least one more stop so that the riders can leave! (W19)
• The shapes with the following shape_ids aren't used by any trips: shape IDs (W20)
• Found too many cells (commas) in line line number of file "file". Every row in the file should have the same number of cells as the header (first line) does. (W21)
• Found missing cells (commas) in line line of file "file". Every row in the file should have the same number of cells as the header (first line) does. (W22)