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What you may find helpful is the installation guides under the products on the PDN for your particular installation.

Tara

Pega Academy Support Team

Is it giving compilation errors or incorrect results?

If it is giving compilation errors, please try to resave the when rule and post the errors displayed.

Thanks.

I am not sure what is exact issue here, but in of the scenario we have faced an issue with declare indexes after upgrade. The following post might be useful.

https://pdn.pega.com/forums/pega-upgrade-center/general-questions/pycom…-

Is the source page context of the when rule different from that of the declare index ?

I think there was a bug in 6.3 which has been fixed in subsequent releases. Can you check whether the When rule is in correct class ?