@Rahul Sukumar , For our issue, based on my research, sometimes old version MP will cause issue. Here are some links for the reference:
https://video2.skills-academy.com/en-us/troubleshoot/system-center/vmm/integration-error-10218
https://www.mrchiyo.com/troubleshooting-opsmgr-to-vmm-connection-error-10218/
Note: Non-Microsoft link, just for the reference.
Here, we suggest to check if there's any old version MP there. If yes, remove them.
To integrate VMM with Operations Manager, we can refer to the following article:
https://video2.skills-academy.com/en-us/system-center/vmm/monitors-ops-manager?view=sc-vmm-2019
Hope it ca help.
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