We tried uploading a Salt Highstate Report and the corresponding Foreman task which processed the upload was actually failing with below error:

Mysql2::Error: Data too long for column 'metrics' at row 1: INSERT INTO `reports` (`host_id`, `reported_at`, `created_at`, `updated_at`, `status`, `metrics`)

We have quite a huge output and therefore it is not unrealistic to have more data in the metric column than a normal MySQL "text" field. We therefore changed the DB Schema manually to "mediumtext" and the upload of the highstate report seems to work now.

Please adjust the corresponding column to "mediumtext".