I have a magento store in 1.9.x CE version. And I had an agency to upgrade this store to magento 2.x CE version in a test environment. They have completed the task but I doubt some data may be missing in the new test version. Can anyone please suggest is there any tool available to compare and verify whether all data has been correctly migrated from M1 version to M2 version?
Thanks and regards
I don't know of a tool to confirm this. It's going to be a bit of a manual task I'm afraid to check customers, sales, orders, cms pages, promotions and other core data.
If they have used the official data migration tool, you can be pretty confident that the data has been migrated. It will only have the data that was migrated on the day that the took the database from your Magento 1 install however. So before launching the Magento 2 store, the agency will likely need to run through the data migration process again to get all of the new data that's changed since, i.e. new orders and customers.