Hi Usuario00,
Welcome to the community,
With the explanation provided - you are in one of below situations.
1) Snapshots taken for the VM but not deleted gracefully - leftover delta files in the data store which got fixed in new version vSphere 5.x with the option - consolidate disk files
2) Snapshot Backups ran against the VM and created multiple delta files and failed to delete the snap. As you have 512 GB disk which is most likely reason for giving such trouble.
file <unspecified filename> is larger than the maximum size supported by datastore <unspecified filename>"
What is the size of data store 3 where your 512 GB disk is located? What is the block size of data store 3? Also what is the block size of destination data store where you are trying to migrate.
I strongly recommend not to delete any disk files when they are linked by snapshot chains - it will cause permanent data loss
You need to browse the data store and copy the VMX file. Make a note of current virtual disk files and note them in your notepad. Once all the required details are captured then you can either use VMKFSTOOLS to clone the individual disk files with the chain of 32 at maximum. Check below article for more details.
Alternatively - If your customer agree for little data loss then identify the Parent disk file and create new VM with that file. Finally attach other two disks to new VM.