When you use SharePoint Migration Tool and migrate any SharePoint 2013 site (with "Site Feed" feature ENABLED) to pre-created Communication site, "Newsfeed.aspx" page (https://tenantName.sharepoint.com/sites/siteName/newsfeed.aspx) appears to be broken. An additional WebPart is added to the page, and both display the following error:
Web Part Error:A Web Part or Web Form Control on this Page cannot be displayed or imported. You don't have Add and Customize Pages permissions required to perform this action. Correlation ID: fc1c189f-e07c-1000-b42a-e22218e27e28.
See the following screenshot:
"Newsfeed.aspx" cannot be modified by Site Owner (or even Tenant admin), as it is not allowed in SPO. So it remains broken forever.
For the ones, who might hit this issue - there is an easy workaround. After you pre-create a Target site (and before you start SPMT migration session), you need to Disable "DenyAddAndCustomizePages" for that particular site using the following command: