Claims error when Processing ops.

I am processing a TTL file as the target content using the following line of code:
ops = synchronizer.synchronize(source_content, target_content)

Also. I am printing the exceptions:

ops = synchronizer.synchronize(source_content, target_content)
for op in ops:
try:
res = op.execute(adapter)
if not res.successful:
print(f"Error synchronizing triple: {res.message}")
except ValueError as exv:
print(f"Value Error: synchronizing triple: {exv}")
except NotImplementedError as exn:
print( f"NotImplementedError: synchronizing triple: {exn}")
except Exception as ex:
print( f"Exception: synchronizing triple: {ex}")

This is the error I am getting:
Exception: synchronizing triple: 'claims'

I would appreciate any pointers as to why I am getting this error when processing the TTL file.