The referencing phrase &1 &2 could not be locked

Message type: E = Error

Message class: /SEHS/PH_CM_DATA - EHS: Phrase Data (Phrase Header, Phrase Item, Phrase Ref.)

Message number: 002

Message text: The referencing phrase &1 &2 could not be locked



What causes this issue?

The referencing phrase &v1&-&v2& from the active library could not be
locked. This phrase is currently being processed by another user.
For this reason, the reference phrase &v3&-&v4& can neither be merged
into the active phrase nor updated.

Error message extract from SAP system. Copyright SAP SE.