The warning message below is encountered when migrating content:
"Managed metadata term guids not found" exception is thrown if the Taxonomy Term GUIDs in source and target environments don't match.
Following is the list of possible reasons that could have to lead to this behavior:
1a) Close the Content Matrix Console.
1c) Find "UseExistingTargetTerms" and set its value to True.
1d) Save the file, then re-launch the Content Matrix Console.
2) Explicitly map the GUIDs of Taxonomy Terms/Term Sets/Term Groups that do not match between source and target. See link below for steps:
Note: If the Term Store was accidentally copied initially with "Resolve managed metadata by name and hierarchy" selected, all taxonomy objects GUIDs will be different. In that case, you might want to consider recopying the Term Store as explained in the prerequisites below.
3) On the job configuration window, de-select all Managed Metadata options except for "Map term stores for migration", then run the migration.
Prerequisites for Migrating Managed Metadata
Migrate the Term Store in advance, using "Paste Managed Metadata Term Stores" to migrate global terms, and "Managed Metadata Local Sites Collection Group" to copy local site collection groups. See link below for instructions:
Note: Configure Managed Metadata Options tab to allow GUID preservation of Term Groups/Term Sets/Terms: