Perf-O-Meter saying: Exception: '_required_names'

CMK version: 2.0.0p1 (CRE)
OS version:Raspian

Error message:
Exception: ‘_required_names’

Tried some new code out in my InternetMetrics.py (located in: /omd/sites/“sitename removed”/local/share/check_mk/web/plugins/metrics)
It didn’t work, and I went back to my original metrics-file (that has worked perfectly for months) but now all the graphs (Perf-O-Meters etc.) doesn’t show up anymore. It just says: “Exception: ‘_required_names’”
Where is the setting I need to change back?
I assume that when I changed my metrics-file it somehow changed a setting in the system and for some reason this setting doesn’t change back after I changed the metrics-file back.

What is the problem can only be said if we see the metric definitions.

There aren’t any… that’s the problem. I deleted them so I went back to basic/raw/standard installation again, and then they stopped working.