Date parse failed on kibana index update

Hello,

ELK 7.2.0
Windows
I am using the 8.0 Upgrade assistant in Kibana.
It appears that a MM argument without the leading 0 gives an index warning but the upgrade assistant (parser) cannot handle it.
I am getting the following error from the upgrade assistant:

{"type":"illegal_argument_exception","reason":"failed to parse date field [4/28/2017] with format [MM/dd/yyyy]","caused_by"

The Warning for the same index:
This index has date fields with deprecated formats: [[type: qapass, field: date, format: MM/dd/yyyy, suggestion: 'y' year should be replaced with 'u'. Use 'y' for year-of-era.]]. Use new java.time date format specifiiers.

Can the upgrade assistant fix this in the next pre-8 version, or possibly give a logstash config to pull from the bad date index, fix the date, and push to a new index?

The 8.0 release of the Elastic Stack is still in very much in development. This sounds like a pre-release bug. You might file an issue on GitHub. https://github.com/elastic/kibana/issues/new/choose