expected value after metric, got "MNAME"

[ray1mori]

Hey. During an active call, Prometheus gives an error expected value after metric, got "MNAME"
promtool check metrics says "error while linting: text format parsing error in line 3: expected float as value, got" " "
After the call ends, everything works again.
How can you fix this error so that you can watch active calls?

[tainguyenbp]

What asterisk version are you using ?