Reason to set MaxErrorCount along with Propogate value for Excel Files

Question

Hi,
I had an ETL earlier which processed CSV files from a folder. The requirement was to load the error files into a Rejected folder but continue to process all the files from the source Folder. This requirement was satisfied by setting the value of the
system variable "Propogate" in EventHandler section for DataFlowTask to "false".
MaxErrorCount value for the ForEach Loop is having its default value as "1".
When tested, it was working perfectly fine
Now currently there is an Excel file as source having same requirement as above. But even when then variable "Propogate" was set to "false" as above, the execution was getting stopped when an error file was found.
Later I found the below link :
http://social.msdn.microsoft.com/Forums/sqlserver/en-US/0065b5c2-f633-4cbf-81f9-031d1ed25555/how-to-skip-wrong-excel-files-ignore-errors-on-ssis-foreach-task
As mentioned in the link, I have done below changes
1)Set MaxErrorCount for ForEachLoop to 1000
2)"Propogate" variable is set to false
Now this is working perfectly fine.
Can you please let me know why did the setting of "Propogate" worked for CSV but did not work for Excel. For Excel files why was an additional setting for MaxErrorCount  was required.
It would be very much helpful if I can get a detail information on the above
Thanks,
Raksha
Raksha

Answer 1

Hi Raksha,
In you SSIS package, setting the Propagate system variable to False of the Event Handler prevents the Data Flow Task (DFT) propagating its failure to its parent container. For the ValidateMetadata property of a Data Flow Task Component, it doesn’t only affect
the DFT at design time but also at runtime. During the Validation phase, a component is supposed to check to make sure that the cached metadata in the package is still in sync with the underlying table/view/query. If there is a mismatch, the component returns
a special status (VS_NEEDSNEWMETADATA). When this happens at design-time, SSIS triggers a metadata refresh by calling ReinitializeMetadata(). At runtime, this results in an error.
In your scenario, by setting the ValidateMetadata property to false, the error of the DFT is avoided, hence, you don’t need to set the MaxErrorCount to a value more than 1.
For more information about how ValidateMetadate property works, please see Matt’s answer in the following thread:
http://stackoverflow.com/questions/3297097/validateexternalmetadata-property-what-exactly-does-this-do 
Regards,
Mike Yin
TechNet Community Support