Purchase requisition &, item &, not released for ordering

What causes this issue?

A <GL:purchase_requisition>purchase requisition</> must be released
(approved) by all <GL:release_point>release points</> included in the
<GL:release_strategy>release strategy</> assigned to the requisition.

How to fix this error?

Determine which release points still have to release this requisition.
You cannot process the purchase requisition further until its final
release.

Error message extract from SAP system. Copyright SAP SE.