The Tasks module on the Modern UX does not load due to an API-1019 : Could not process the request due to internal error

Document ID : KB000127071
Last Modified Date : 14/02/2019
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Issue:
STEPS TO REPRODUCE:
1. In Classic UI go to Studio > Objects > Tasks
2. On the Attributes list, set a Specific Default Date for the Start and Finish dates
   example: 01/01/2018
3. Login to the Modern UX
4. Go to the Tasks Module

Expected results: The tasks module to load and display
Actual results: API-1019 : Could not process the request due to internal error
Cause:
This is caused by DE46290
Resolution:
This is fixed within 15.6

Workaround: 
The reason the issue is happening is because the default value of a date field is coming as a String value when the Default Date is configured as Specific Date and not as a Rolling Date.
Set the default value to a Rolling Date like Today, Tomorrow
Additional Information:
Log files show the following error:

ERROR 2018-12-26 13:04:41,792 [http-nio-14001-exec-320] ppm.rest (clarity:myuser@mycompany.com:20207070__34E372D6-6042-4559-BA4A-367F5D6F8C58:PPM_REST_API) Exception processing request
java.lang.ClassCastException: java.lang.String cannot be cast to java.util.Date