I had problems upgrading a WSP containing one or more Page Layouts?
Unable to edit or update a Page Layout?

Related article: Editing SharePoint Webparts embedded within Page Layouts https://www.sjlewis.com/2015/10/15/editing-sharepoint-webparts-embedded-within-page-layouts/

• Navigate to the site settings of the root website (within a site collection)
• Click Master pages and page layouts and locate the Page Layouts
• Make a note of the file name, for example: PageLayout.aspx

Note: you will not be able to view or edit the page layout directly by clicking on the title or a menu item

• Using one of the URL below, change the tenant and file name to create the required URL:

https://tenant.sharepoint.com/_catalogs/masterpage/PageLayout.aspx?Contents=1

• Once the Web Part Page Maintenance page has loaded, starting from the top select the duplicate webparts and then click Delete

You should now be able to complete the update or upgrade action you previously set out to do.