Whitelisting of file extentions in sharepoint folder

Hi sam2024,

Unfortunately, there is no place to set up a file type whitelist in SharePoint Online. We can only specify those files that cannot be uploaded to SharePoint. Maybe you can add all the common file suffixes in windows to the Blocked File Types and remove doc and txt to meet your needs. If there are other types of files that are subsequently prohibited from being uploaded, you can add them to the Blocked File Types.

Here are some other options:

1. Information Rights Management (IRM): SharePoint Online allows you to use Information Rights Management to restrict what users can do with documents, such as preventing them from downloading, printing, or copying text. While this doesn't precisely restrict file types, it can help protect the content of your documents.

2. Customized Form and Workflow: You can create a custom form for uploading files to the SharePoint library. In the form, you can add a validation step to check the file extension before allowing the upload. If it's not one of the allowed extensions, the form can reject the file. This can be done using SharePoint Designer, PowerApps, or other development tools.