those messages normally suggest that something iw wrong with feedback.
When they come in pairs, it means that two circuits for same device are not working.
Most of the time that mean resolver cable is unplugged from the motor (or RDC) or maybe RDC channel is not ok.
When multiple axes report the same problem, the problem is usually something common to all axes such as RDC or RDC power or RDC data channel. both power and data are on same cable (X21-X31) so check for oxidized, bent, or pushed out contacts and both sides and at each connector.
Funny thing is that one message is only affecting odd numbered axes (1,3,5,7). That is rather interesting and unique pattern, possibly software error or misconfiguration.
what is the robots history? how did you arrive to this scenario?
If a plant electrician moved the resolver cable (the one that runs from the KRC to the robot base), check the pins on both ends. Those cables are particularly vulnerable to having their male pins pushed down into the housings whenever someone is careless about screwing the connectors together. Ditto for the resolver cables on the individual motors. Once they've been damaged, it's not hard for these pins to look fine, but actually be loose enough that they won't make contact with the female side. If you grab each pin with needle-nose pliers and (gently!) push/pull on them, they should have less than 1mm of axial play -- if they "sink" into the connector housing when you push on them, that's your issue. Sometimes you can fix this simply by pulling on the pins until they seat in the socket again, but they will still be fragile, and require extra care when being connected -- you will need to be very sure the connectors are aligned properly before you begin screwing them together.
