To reproduce:
set protocols bgp local-as 100 set protocols bgp peer-group foo remote-as 200 set protocols bgp peer-group bar-baz remote-as 201 set protocols bgp peer-group bar_baz remote-as 201 set protocols bgp neighbor 192.0.2.1 peer-group foo set protocols bgp neighbor 192.0.2.2 peer-group bar-baz set protocols bgp neighbor 192.0.2.3 peer-group bar_baz commit [ protocols bgp neighbor 192.0.2.2 peer-group bar-baz ] protocols bgp peer-group bar-baz doesn't exist [[protocols bgp 100]] failed Commit failed
FRR allows a peer-group to contain a hyphen
router bgp 100 neighbor foo-bar peer-group neighbor foo-bar remote-as 200 neighbor 1.1.1.1 peer-group foo-bar !
VyOS 1.3 and older does not support this due to a regex when validating the peer-group name
vyos@vyos# set protocols bgp 100 peer-group bar-baz remote-as 201 malformed peer-group name bar-baz Value validation failed Set failed