Oh great, thank you @johnb.
Without hailing it as a success yet, I think we might be into a real improvement here.
Here's an explanation.
Looking into the recent problems with uploads, a pattern that struck me was that while some users were consistently having troubles, others weren't experiencing any problems at all. Also, even users having the problem seemed to be able to upload some of the photos, but not all.
By way of deduction, this brought to mind three possible reasons for this happening: either (1) our security application firewall was incorrectly blocking your images files form uploading, the AI engine therein identifying them as malicious files. Or, (2) resource (memory) limitation settings on the server might have caused some image uploads to bail out, while others would complete ok. Thirdly, (3) some unsupported feature or format in these particular images could have been causing our image processing engine to fail.
I spent time today investigating these options. I could eliminate the firewall alternative fairly quickly, while investigation of our extended logging assured me that the uploader wasn't hitting into any memory limitations.
What struck me was that all users experiencing problems seemed to have kept uploading photos using mobile devices - either iPhone/iPad or Android. Following that lead, I performed an entire series of random uploads using my iPhone and various images directly from the phone's camera roll. I was soon hitting upon a problem similar to yours - some of the images were refusing to upload leaving a notorious "Error: Error" message. The results were repeatable - trying to upload the same files again would yield the same error no matter how many times an upload was attempted.
Looking back into the logs again, I discovered another lead: most of the offending images appeared to be shot in portrait orientation.
I'll explain why this matters. A few years back, the makers of iPhone (and later also Android) introduced a way of handling picture files which was different from, and incompatible with the way JPEG files were saved by most other programs or used at the web. A portrait picture taken with your iPhone isn't really stored in portrait orientation, instead it only carries a few bits of orientation information in its (EXIF) metadata. That's why, when uploading a portrait picture from such a device, the receiving website must reprocess the image and rotate it to actual portrait orientation as used on the web, otherwise the picture would appear in your browser as lying on a side.
iModeler's image processing engine does this routinely for all photos uploaded directly from mobile devices. A discovery today was that a component responsible for image rotation was misconfigured during our server transition, causing your (and presumably only portrait) photos to fail. Doh! From there, it was a fairly easy fix.
This is what I think has been happening, please let me know if the above story is consistent with your experience. If there are any deviations or other outstanding problems with uploads, I'd appreciate further information.
Hope this also improves upon upload problems experienced by @gblair, @paulwoodyvanacker and @scalerambush.
