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Advocate I
Advocate I

Initializing and Updating Boolean

When initializing or setting a Boolean type variable you're able to put in a value. However, instead of it being chosen via a dropdown (would make the most sense since Flow is very graphically intuitive for the most part) you must type in a value; I'd consider that change to be more of a feature request, but it would also resolve the "bugs" if it was a consistent manner throughout.


The bug:

  • When you type in the most obvious values, True or False, it presents no error and allows you to save the Flow. However, the value is apparently case-sensitive and must by typed in all lowercase letters as 'true' or 'false' (without quotes of course).
    • In addition, if you type Yes or No or yes or no you receive a contextual message advising you that it is a Boolean variable and required a Boolean value. This makes it even more odd because the dropdown (mentioned next) is Yes or No.
  • When you can choose valid values via dropdown (as is the case when using a Boolean variable for a comparison), the options are 'Yes', 'No', and 'Enter custom value'.
    • If you choose Yes or No, then save the Flow and go to review the comparison again, it updates to bool('false') or bool('true') (which doesn't match the dropdown so there's some intuitiveness lost there as well).
    • If you choose 'Enter custom value' it lets you type in or add Dynamic Content.
    • I have also see where the comparison doesn't give me a dropdown to choose from until I add the Boolean variable as the option to compare against (no other Dynamic Content makes the arrow appear), then the arrow appears and I can choose one of the three options.


EDIT: Another bug has cropped up with Boolean variables... I'm able to use the 'Set Variable' action successfully to change a boolean variable from false to true and save my Flow; however, when I make other changes and try to save I receive 'Definition contains invalid parameters'. When I expand every item I see that some of Set Variables for the boolean variable are now asking 'Enter a valid number' and I cannot save the Flow now until I delete every Set Variable that's manipulating the Boolean variable.

Community Support
Community Support

Hi @tkude,


Thanks for the feedback.

Sometimes the Compose and the Variable action would need to be re-defined in order to use it again when editing the flow.

And for the Yes or No, and the true or false, I will collect this as a feedback, to suggest Flow PG to make this unified.




Community Support Team _ Michael Shao
If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.
Kudo Collector
Kudo Collector

HI, you dont have to delete the set variable action.


Create two different initialize variable actions set to boolean, then while saving you get Definition contains invalid parameters.

You find the set variable action with the red border that says Enter a valid number

you set the Name dropdown in the set variable to the other boolean initialize variable action than switch it back to the correct one once again and after that retype true/false into value text field


you have to do it for every set variable boolean in the WF (except the first one)


this is a rookie mistake MS... apparently I am having a bad week with ms flow as half of my WF stopped working couple of days ago 😞


Sometimes the Compose and the Variable action would need to be re-defined in order to use it again when editing the flow.





I'm assuming that's considered a bug and has been put into a queue for review at some point? Obviously it isn't expected behavior...

Frequent Visitor

Three years later and the naming scheme hasn't been unified.  I also receive no errors when using "True" as opposed to "true" but the flow will fail with an error.

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