I\'m getting this error from SQL Server on SSMS 17 while running a giant query:
Conversion failed when converting the ****** value \'******\' to data type
I had the same error when trying to combine an nvarchar and int into a single string. Usually it tells me the data type where I screwed up but occasionally its the error you got.
I went from
SELECT ';' + [myNumber]
to
SELECT ';' + CAST([myNumber] as nvarchar(100))
which solved it for me.
So as the others have suggested, I guess it is something similar and you need to CAST or CONVERT one of your values to match the rest.