Hi Shoshanah. This was probably a temporary error, perhaps only visible from Aleš's server, at the time the WikiTree link checks were running. Since the link does work fine, you can mark the suggestion as fixed: hopefully it will not recur. If it does recur, mark it false.
Aleš may be able to label the site as a well-known stable one where such errors are spurious and should not be reported. This might save time for many WikiTree members. To draw his attention, you could edit your question and add the tag ales .