Error & when adding to market data buffer

What causes this issue?

Error when adding data to market data buffer.

System Response

Error 1: Market database blocked by another user.
Error 2: R/3 System error.

How to fix this error?

Error 1: Repeat request later
Error 2: Notify SAP R/3 System administrator (problem with
Enqueue server)

Error message extract from SAP system. Copyright SAP SE.