MySQL syntax error in field_sql_storage.module

When attempting to publish a revision to a "carousel" node type with a Link field, get a syntax error for some URLs but not others. Any previous link is blanked. Other modules used include internationalization, context and pathauto. Here is the error where each x represents an alphabetic character:

Type php
Message PDOException: SQLSTATE[42000]: Syntax error or access violation:
1064 You have an error in your SQL syntax; check the manual that
corresponds to your MySQL server version for the right syntax to use
near ')' at line 1: INSERT INTO {field_data_field_url} (entity_type,
entity_id, revision_id, bundle, delta, language, field_url_url,
field_url_title, field_url_attributes) VALUES (:db_insert_placeholder_0,
:db_insert_placeholder_1, :db_insert_placeholder_2,
:db_insert_placeholder_3, :db_insert_placeholder_4,
:db_insert_placeholder_5, :db_insert_placeholder_6,
:db_insert_placeholder_7, ); Array ( [:db_insert_placeholder_0] => node
[:db_insert_placeholder_1] => 1234 [:db_insert_placeholder_2] => 2345
[:db_insert_placeholder_3] => carousel [:db_insert_placeholder_4] => 0
[:db_insert_placeholder_5] => und [:db_insert_placeholder_6] =>
http://www.x-x.xxx/xxxxxxxxx/xxxxxx-xxxxx-xxxxx-xxxxxxxxx-xxxxxxxxxxx-xx...
[:db_insert_placeholder_7] => ) in
field_sql_storage_field_storage_write() (line 451 of
[...]/modules/field/modules/field_sql_storage/field_sql_storage.module).
Severity error