Wherever the system should have posted an entry automatically and could not, a row is left here (Open by default).
Causes
Usually: no fiscal year covers the date, the period is closed, the document is in a foreign currency, or a required account is missing. System accounts cannot be deleted or renamed in the application, so a missing account is rare.
Retry
Retry re-posts from the source document and marks the row resolved on success ("Posted as N", "Already posted"). Retry all (Open view) tries up to 25. Limits: five attempts per row, 60 seconds between tries, 30 single and 4 bulk retries a minute per person. Errors: "Nothing left to post", "Cannot be replayed automatically" (foreign currency, for example), "Retried too recently", "Too many failed attempts", "Still failing".
Mark Resolved
Marks the row only; it posts nothing and asks nothing. Use it after you posted the entry by hand.
Alerts
Each failure raises a notification to all admins (English text only), optionally an email, and a daily reminder while rows stay open. A missing balanced entry never unbalances the trial balance; it shows up in Sub-ledger Reconciliation.