PDOException when uploading GPX file, if raw GPX previously was too big

When I try to create a GPX layer with too big raw GPX data, I got an PDOException (PDOException: SQLSTATE[22001]: String data, right truncated: 1406 Data too long for column 'data' at row 1: INSERT INTO {openlayers_layers} (name, ...).
When I click back, and choose a different method, for example upload a file, the file upload also gives the same PDOException. When I refresh the page, the layer with the uploaded gpx file is created normally.