Read only SharePoint Online in June? (MC141047)

We had the same type of message last year. I raised the issue with my local Microsoft support team, and only after applying significant pressure, did they narrow it down for us.

These types of messages are ridiculous.  They provide no actionable info - they apparently just hope that you won't call support if your SharePoint sites are randomly set to read-only.  Good luck if causes an interruption to your business.

Here's the message we got:

Planned Capacity Balancing Maintenance

MC89892

Published On : January 5, 2017

Expires On : March 6, 2017

We have maintenance planned for SharePoint Online. In order to increase datacenter capacity, we'll be conducting planned balancing operations during the month of January.

How does this affect me?

During this scheduled maintenance, your SharePoint content will be read-only for up to 60 minutes during off-peak hours.

What action do I need to take?

No action is required on your part.