The exact number of columns that cause the job to fail is variable and is based on the length of the column names and the number of validation-enabled columns. Long column names are at—or close to—the maximum allowable length of 26 characters. To avoid this problem, keep the number of validation-enabled columns below 60 and/or the length of the column names short. A work around is to enable all trust/validation columns before saving the base object to avoid running the synchronization job.