Dash 1.6.0 needs defined (max) core components..

[pythononwheels]

ERROR: dash 1.6.0 has requirement dash-core-components==1.5.0, but you'll have dash-core-components 1.8.0 which is incompatible.
ERROR: dash 1.6.0 has requirement dash-html-components==1.0.1, but you'll have dash-html-components 1.0.2 which is incompatible.
ERROR: dash 1.6.0 has requirement dash-renderer==1.2.0, but you'll have dash-renderer 1.2.4 which is incompatible.
ERROR: dash 1.6.0 has requirement dash-table==4.5.0, but you'll have dash-table 4.6.0 which is incompatible.

Need to adapt the requirements_dash file.
Still works, though.

[pythononwheels]

I checked the unversioned requirements.

dash
dash-core-components
dash-html-components
dash-renderer
dash-table
dash-daq
pandas
numpy

Leads to:
(As of 07 Feb 2020)

dash==1.9.0
dash-core-components==1.8.0
dash-daq==0.3.3
dash-html-components==1.0.2
dash-renderer==1.2.4
dash-table==4.6.0

Which works just fine without complaining about
incompatibilities for PythonOnWheels >=0.922