diff --git a/lib/media/webm_segment_index_parser.js b/lib/media/webm_segment_index_parser.js
index b9fe2153ad..1e8421472a 100644
--- a/lib/media/webm_segment_index_parser.js
+++ b/lib/media/webm_segment_index_parser.js
@@ -127,7 +127,7 @@ shaka.media.WebmSegmentIndexParser.prototype.parseWebmContainer_ = function(
     shaka.log.error('Not an EBML element.');
     throw new shaka.util.Error(
         shaka.util.Error.Category.MEDIA,
-        shaka.util.Error.Code.WEBM_EBML_ELEMENT_MISSING);
+        shaka.util.Error.Code.WEBM_EBML_HEADER_ELEMENT_MISSING);
   }
 
   var segmentElement = parser.parseElement();
diff --git a/lib/util/error.js b/lib/util/error.js
index 934b4a54c3..7ba84a7d9b 100644
--- a/lib/util/error.js
+++ b/lib/util/error.js
@@ -53,8 +53,13 @@ shaka.util.Error = function(category, code, var_args) {
  * @export
  */
 shaka.util.Error.Category = {
+  /** Errors from the network stack. */
   'NETWORK': 1,
+
+  /** Errors parsing text streams. */
   'TEXT': 2,
+
+  /** Errors parsing or processing audio or video streams. */
   'MEDIA': 3
 };
 
@@ -64,27 +69,134 @@ shaka.util.Error.Category = {
  * @export
  */
 shaka.util.Error.Code = {
+  /**
+   * A network request was made using an unsupported URI scheme.
+   * <br> error.data[0] is the URI.
+   */
   'UNSUPPORTED_SCHEME': 1,
+
+  /**
+   * An HTTP network request returned an HTTP status that indicated a failure.
+   * <br> error.data[0] is the URI.
+   * <br> error.data[1] is the status code.
+   */
   'BAD_HTTP_STATUS': 2,
+
+  /**
+   * An HTTP network request failed with an error, but not from the server.
+   * <br> error.data[0] is the URI.
+   */
   'HTTP_ERROR': 3,
+
+  /**
+   * A network request timed out.
+   * <br> error.data[0] is the URI.
+   */
   'TIMEOUT': 4,
+
+  /**
+   * A network request was made with a malformed data URI.
+   * <br> error.data[0] is the URI.
+   */
   'MALFORMED_DATA_URI': 5,
+
+  /**
+   * A network request was made with a data URI using an unknown encoding.
+   * <br> error.data[0] is the URI.
+   */
   'UNKNOWN_DATA_URI_ENCODING': 6,
+
+  /** The text parser failed to parse a text stream due to an invalid header. */
   'INVALID_TEXT_HEADER': 7,
+
+  /** The text parser failed to parse a text stream due to an invalid cue. */
   'INVALID_TEXT_CUE': 8,
+
+  /**
+   * The text parser failed to parse a text stream due to invalid cue settings.
+   */
   'INVALID_TEXT_SETTINGS': 9,
+
+  /**
+   * Some component tried to read past the end of a buffer.  The segment index,
+   * init segment, or PSSH may be malformed.
+   */
   'BUFFER_READ_OUT_OF_BOUNDS': 10,
+
+  /**
+   * Some component tried to parse an integer that was too large to fit in a
+   * JavaScript number without rounding error.  JavaScript can only natively
+   * represent integers up to 53 bits.
+   */
   'JS_INTEGER_OVERFLOW': 11,
+
+  /**
+   * The EBML parser used to parse the WebM container encountered an integer,
+   * ID, or other field larger than the maximum supported by the parser.
+   */
   'EBML_OVERFLOW': 12,
+
+  /**
+   * The EBML parser used to parse the WebM container encountered a floating-
+   * point field of a size not supported by the parser.
+   */
   'EBML_BAD_FLOATING_POINT_SIZE': 13,
+
+  /**
+   * The MP4 SIDX parser found the wrong box type.
+   * Either the segment index range is incorrect or the data is corrupt.
+   */
   'MP4_SIDX_WRONG_BOX_TYPE': 14,
+
+  /**
+   * The MP4 SIDX parser encountered an invalid timescale.
+   * The segment index data may be corrupt.
+   */
   'MP4_SIDX_INVALID_TIMESCALE': 15,
+
+  /** The MP4 SIDX parser encountered a type of SIDX that is not supported. */
   'MP4_SIDX_TYPE_NOT_SUPPORTED': 16,
+
+  /**
+   * The WebM Cues parser was unable to locate the Cues element.
+   * The segment index data may be corrupt.
+   */
   'WEBM_CUES_ELEMENT_MISSING': 17,
-  'WEBM_EBML_ELEMENT_MISSING': 18,
+
+  /**
+   * The WebM header parser was unable to locate the Ebml element.
+   * The init segment data may be corrupt.
+   */
+  'WEBM_EBML_HEADER_ELEMENT_MISSING': 18,
+
+  /**
+   * The WebM header parser was unable to locate the Segment element.
+   * The init segment data may be corrupt.
+   */
   'WEBM_SEGMENT_ELEMENT_MISSING': 19,
+
+  /**
+   * The WebM header parser was unable to locate the Info element.
+   * The init segment data may be corrupt.
+   */
   'WEBM_INFO_ELEMENT_MISSING': 20,
+
+  /**
+   * The WebM header parser was unable to locate the Duration element.
+   * The init segment data may be corrupt or may have been incorrectly encoded.
+   * Shaka requires a duration in WebM DASH content.
+   */
   'WEBM_DURATION_ELEMENT_MISSING': 21,
+
+  /**
+   * The WebM Cues parser was unable to locate the Cue Track Positions element.
+   * The segment index data may be corrupt.
+   */
   'WEBM_CUE_TRACK_POSITIONS_ELEMENT_MISSING': 22,
+
+  /**
+   * The WebM Cues parser was unable to locate the Cue Time element.
+   * The segment index data may be corrupt.
+   */
   'WEBM_CUE_TIME_ELEMENT_MISSING': 23
 };