Thank you for the post @rameshkumarparathi
This looks like general connectivity issue between Firewall and Panorama. Could you go to: Panorama > Managed Devices > Summary, then confirm status of this Firewall. If this Firewall is disconnected from Panorama, then this is not related to Template.
On Firewall side confirm that Panorama is registered under: Device > Setup > Management > Panorama Settings. Also make sure that Serial Number of the Firewall is the same as the one registered in Panorama. If there is no issue with these 2 settings, then I would move to connectivity troubleshoting: https://knowledgebase.paloaltonetworks.com/KCSArticleDetail?id=kA10g000000ClaWCAS
Once connectivity is restored, you should be able to see connected status and use Firewall in Template Stack.
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