How to Avoid Item addition when attachment is invalid.
Published May 01 2019 04:02 PM 189 Views
First published on TECHNET on Feb 18, 2015

This post is a contribution from Jaishree Thiyagrajan, an engineer with the SharePoint Developer Support team

When we add a files with name containing only symbols like "([{_$%]}).txt" as an attachment to a list, we will see the error "The file/folder name that contains characters that are not allowed" & the attachment will not be added. But the item will be added.

We need to create a ItemEventReceiver and use ItemAttachmentAdding method to achieve the required functionality

public override void ItemAttachmentAdding(SPItemEventProperties properties)



//write your logic to check for valid filename and cancel it out if you do not want to save the attachment.


We cannot use ItemAdding event for the above requirement as we would not able to get the attachment name because the ListItem is null.

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‎Aug 27 2020 03:36 PM
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