Very rarely, a buyer may get the error message
Request has expired after clicking their download link. This indicates a glitch at Amazon S3, which we use for long-term download storage and delivery. While this error is very unusual, we don't have any control or scrutiny over it, so in this case the best resolution would be to issue the buyer a replacement link in Seller Admin > Manage Buyers > Send free download link.
However, if your buyer sees this message after clicking their download link:
This download link (https://www.e-junkie.com/ecom/df.php?txn_id=XXXXXXXXXXXXXXXX&client_id=YYYYYY&d_id=ZZZZZZZZZZ) has expired. Please contact the merchant at [your Display Email here].
That will only happen when the link we issued them actually is expired according to your product's link expiration settings in our Seller Admin. Whenever you add/edit a download product, you will find expiration settings for the maximum number of Attempts you will allow on each buyer's link, and you can also optionally specify a time limit in Hours. The download link we issue to each buyer will expire when it has met the maximum Attempts or Hours (whichever comes first) that you allow.
You can view the number of Attempts made for any buyer's link(s) in your Transaction Log. If the Attempts logged there match the maximum Attempts you have defined in the product's settings, that confirms the buyer's link expired because they used up all the Attempts you allow. If you also impose a limit in Hours, and the present time is more than that many hours after the Processed by E-j timestamp for that order in your log (which is always MST / GMT -7), then that confirms the buyer's link expired because your maximum time limit has passed.
You can reset the expiration on any link in Seller Admin > Manage Buyers > Reactivate Expired Links / Resend Email, where you will need to enter the buyer's Transaction ID (which you can obtain from your Transaction Log) and can optionally choose to re-send thank-you emails with the link to their thank-you/download page. Since reactivating a link would reset the Attempts/Hours countdown on that link, after that point your Transaction Log for that order would only count Attempts made since you last reactivated that link.
Bear in mind it is not technically possible to determine when a download has completed successfully; we can only count how many times the buyer has Attempted to start the download on their link. Attempts count any "hit" on the download link, which can include anti-virus/security software that may pre-scan links for potential computer threats, so these can use up Attempts before the buyer even has a chance to try the link themselves. If a buyer needs to pause and resume a large download, or if their browser or download manager attempts to resume stalled downloads automatically, each restarted download counts as another Attempt on that buyer's link. For these and other reasons, we recommend our default link expiration settings allowing up to 5 Attempts within 120 Hours or, if you prefer to be more restrictive, allow no fewer than 3 Attempts within 24 Hours as a bare minimum.
Another issue we have seen occasionally is when buyers use a "download accelerator" that actually splits the file into several parts to download simultaneously. Each of those concurrent partial-downloads would count as an "Attempt" against their link, which can exhaust all your permitted Attempts all at once and may appear to expire the link prematurely. If this happens, reactivate the buyer's download link (as explained above) and ask them to retry with their download accelerator disabled, just using the standard download function of their Web browser.