Hello @NIRANJANDJ  

One way to achieve your requirement is to use the localization tool available in Constellation (App Studio → Settings → Localization). You can prepare a localization package, for example for English (United Kingdom), and set it as the default for all operators in your system. It is quite time-consuming, because you would need to update the JSON for all other field values as well, even though the only required change would be for “Cannot be blank.”

Another way to achieve your requirement is described in the Pega Support article titled Custom Error Message for Required Field in Constellation (Pega v24.2.2). You can find detailed steps and examples at the following link: https://support.pega.com/conversations/user-experience/custom-error-message-for-required-field-in-constellation-%28pega-v24.2.2%29