Hi !!
Any idea what does it mean
error while executing a Scalar value query for Scalar, .pyDisplay().pyUIActive(1).pyStreamName, on page ‘Declare_pyDisplay’
We get this error readings from log file, using splunk.
Note:- Recently we migrated from pega 8.3 to 8.7
Built on application is UI-Kit
@AbhishekC1725 Can you find anything more about the context where this is logged, for example in the Pega logs with the timestamp you have from Splunk? This can be a lot of things, I see that the .pyStreamName property is an Identifier for most classes but the operation (i.e. a Property-set) is failing. I don’t see a direct reference in the Declare_pyDisplay data page unfortunately. A stack trace would be truly helpful 
@BasG0629 Ok, Will Check from pega logs also.
@AbhishekC1725 any solution you got to fix that issue?
same issue I am also facing in my project and I did some analysis.
this when rule is pyIsPerformScreenFlow failing
Declare_pyDisplay.pyDisplay(pyPortal.pyPortalPages(1).pyHarnessName).pyUIActive(1).pyStreamName
in above condition this value pyPortal.pyPortalPages(1).pyHarnessName is returning empty and passing like this
Declare_pyDisplay.pyDisplay().pyUIActive(1).pyStreamName and getting scalar error.
Please let me know any fix is there for above issue.
@GirishK17093040 No Solution we get yet.
@GirishK17093040 please log a support issue via the MSP and let us know the INC here.
This issue comes when your DB table column is holding different datatype lets say Number but you are trying to save string value for it for example 123_1. So pega throws error immediately while setting string value to your decimal property. basically whenever types mismatch with data and columns definition.
please log a support issue via the MSP and provide the INC id here so we can help track it.