Premature "Nothing more to learn"

Problem

Mike S. wrote:

I have about 1000 outstanding elements. While learning, I suddenly see "Nothing more to learn". Nothing seems to help. I tried sorting repetitions and many other tricks. I noticed that when I open View : Outstanding, my first element is marked with a red-cross [repair/recovery] icon. This may explain my problem, but how I get rid of this element, or how can I resume repetitions? I planned two hours of heavy learning, and spent most of this time on trying to solve this problem. I think SuperMemo should be a bit smarter and know how to skip or delete a problematic element

Answer

You are right. If a deleted or empty or zero element ends up in the outstanding queue, it will block learning. This will be remedied as soon as possible. The only excuse we have is that you are the first case reported. That weakness has been there for a decade (or more) and nobody noticed. You might be the first case affected. Your problem will disappear tomorrow because the outstanding queue is built anew for each single day. Empty elements might end up in the queue as a result of some major mishap, e.g. unexpected shutdown, restart, software crash, etc. It is hard to say why it happened, but it is certainly an extremely rare mishap.

Workaround

You can resolve the problem by deleting Outstanding.sub and OutstandingTopic.sub subsets from your collection's \info folder. This will force SuperMemo to rebuild the outstanding queue. You will need to sort repetition manually because the rebuilt queue will not be auto-sorted.

SuperMemo update

When you update to SuperMemo ver. 18.03 (possibly yet in June 2019), this problem will be resolved. Older versions will not be corrected retroactively due to negligible harm, easy workarounds, and low likelihood of this happening again.