The request URL or the metadata definition is incorrect.

What causes this issue?

The metadata entity with the internal ID '&V1&' has not been found. This
means that the request URL or the metadata definition in BEP (or SAP
Gateway) contains an error.
Possible reasons are
The URL contains a segment with a wrong name. E.g. the requested entity
set or function import does not exist.
The metadata definition is not correct. E.g. the definition of an
association references to an entity set that does not exist. This is
especially likely if two services have been composed via method
INCLUDE_MODEL_BY_SERVICE_ID in the BEP Add-On.

System Response

The request cannot be processed.

How to fix this error?

Validate your request URL.
Start with the service document only. Is this request processed
succesfully?
Build up your your request URL carefully step by step and make sure to
avoid any spelling errors.
Check the error log. Transaction
<DS:TRAN./IWFND/ERROR_LOG>/IWFND/ERROR_LOG</>
What other errors are showing? What does their long text tell you?
If you are a developer, use the functions "Active Source" and "Call
stack" to start your debugging.

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.