When following the online manual of Portal 4.3.1 to migrate the Portal 4.2.x Jarvis data to the external Jarvis used for Portal 4.3.1 and using the command: # java -jar migration-tools.jar --source http://<Portal FQDN>.com:8080 --target http://<External Jarvis FQDN>:8080 --product ca_apim --pagesize=5000 ProcessID-  INFO Main:75 - Starting Tool in Migration Mode. ProcessID-  INFO Main:103 - 'from' is not given. Assuming migration from beginning. ProcessID-  INFO Main:109 - 'to' is not given. Assuming migration until current time. ProcessID-  INFO Main:127 - Source Jarvis API URL: http://<Portal FQDN>.com:8080 ProcessID-  INFO Main:128 - Target Jarvis API URL: http://<External Jarvis FQDN>:8080 ProcessID-  INFO Main:129 - Product ID: ca_apim ProcessID-  ERROR Main:144 - Error occurred during Migration: Error reading product metadata for ca_apim on Source Env http://<Portal FQDN>:8080. Got response null
And Migration fails.
The sample in the online manual refers to default product name (which is also the default portal tenant ID if not changed).
The default is 'ca_apim'.
But customers who have started with a Portal version below 126.96.36.199 or manually updated the PORTAL_TENANT_ID to be different than 'apim' would fail if use the 'ca_apim' as the product in the migration command.
Portal 4.2.x getting ready to migrate to external Jarvis Server using the migration-util command.
Check your portal.conf for the value of 'PORTAL_TENANT_ID' and use this value preceding with 'ca_' for the migration command.
Also, check the product_id by running the below on the Portal: