This stored procedure was working fine, then started throwing this error. It's being used as the main query for an SSRS report. If I put single quotes around the date I select, I get the error, but also see that there are results. If I don't use the single quotes, the query runs and I get no results. As you can see, the parameter is being passed as datetime, converted to varchar and then cast as char. I didn't write the original query, but didn't change anything that had to do with this part. I can't seem to find the reason for it not working now.