I am using an Excel file and an ArcSDE geodatabase to detect the changes using change detector tool.
The output is an excel file with the changes.
The tool runs fine on the small excel file, but as soon excel file exceeds 50000 records the error appears.
Which version of FME and which platform (Win/Mac/Linux) are you on?
I see this error message for Excel reported before. The cause wasn't clear, but there were a couple of suggestions.
1) If the data has geometry, add a GeometryRemover transformer before the Excel Writer.
2) Do you have more than one Writer in the workspace? If so, try with just a single writer to see if that helps.
Sorry I can't give more explicit suggestions. If you still can't get it working I suggest contacting your support rep (either Safe support at safe.com/support or your local reseller). Mention that it might be related to PR#48867. But if you are using an older FME do try upgrading first, as that often fixes problems.
Regards
Mark