I recently completed an upgrade from 5.5R2 to version 6 and applied the latest hotfix. The site builds and serves without issues. I have run into an issue where GetFile.aspx is returning 404 for some document attachments I added prior to the upgrade. Tracing GetFile.aspx, AttachmentManager.EnsurePhysicalFile is returning null although the file is actually present where it should be. The attachment is associated as a file field on a custom doctype.

I've worked through the data end and everything looks fine. The correct GUID is being requested, and that file does in fact exist where I believe it should. I can add new attachments to these documents and they serve without any issues. I have checked file permissions and ensured all the files and folders are set properly. I have also checked the file settings in SiteManager and they are correct, and the same as before the upgrade.

I do not have the API source so some insight into how AttachmentManager ensures that file would be helpful. If its just FileExists some way of verifying the path would be helpful.

Any direction would be appreciated,
Shawn