I *think* it's fixed ... certainly looks right for me now. I'll leave it 24 hours to see if I get any more reports and if not consider it closed.
OK - issue sorted.
Members are allowed to attach files of certain types (such as .jpg images and .pdf documents) to their posts, subject to a maximum file size. When displayed on the bottom of a post for the first time, certain of these file types generate a thumbnail so readers can quickly have an idea of what's in the file before they download it. This thumbnailing process can have rather a large server memory requirement - especially when it's a large .jpf file involved.
The other day, a .jpg was uploaded which was within the maximum file size, but caused the forum software to require more than the maximum memory it's allowed when thumbnailling, causing the server request to crash "blank screen", without even an error log or message. As the thumbnail hadn't been created, every time anyone called for the particular post to be displayed
in the thread and with the attachment offered, the server tried again and crashed again. It was, however, happy to show the post if users selected to print the thread or see it on recents, as neither of those viewing methods offers thumbnails.
The "user solution" is for me to ask members not to upload images larger than 2k x 1.5k pixels. The one the other day was over 4k x 3k. It just contained a lot of flat grey, so the compression applied in the .jpg algorithm in the user's camera had resulted in quite a small file that had passed the server's file size limit test.
I could - but won't - limit the file upload size; the maximum is set where it is for other documents and all I would be doing is fixing one very rare problem and in the process creating a limit that would frustrate more often. If it happens again (once in 12 years so far), please let me know - it's easy for me to resize the rogue image now that I know what I'm looking for.
