Enter a valid building

What causes this issue?

You have entered building "&V1&" which could not be found defined as a
valid building in table T777A.

How to fix this error?

Press F4 to display a list of valid buildings and select one of these.
If you need to define a new building, please and maintain table T777A
in Customizing.

Error message extract from SAP system. Copyright SAP SE.