The date reported there had mixed punctuation and we are unable to parse it: 20170821T1415+0300Z
However we are also not able to parse no punctuation either, i.e. 20171207T124731Z which according to Wikipedia ( 😃 ) is a valid ISO format. Neither Date.parse() nor the chrono library recognises it.
Reported to chrono here: https://github.com/wanasit/chrono/issues/239
TODO: either submit pull request to chrono and/or use a custom parser.