I took over a network a little over a year ago noticed these messages in the logs of some of my layer 2 switches. I did some research and made some configuration changes but the problem was still there. It wasn't until I was setting up Devops net in my building that I learned that my entire building was wired for single mode fiber. When I looked deeper I found that some of my single mode cables were connected to SFP-SR (multimode) instead of SFPs-LR. After I replaced the SRs with LRs the messages went away. Hopefully this helps someone.