I am currently in the process of upgrading one of our customer's solutions from Sitecore 8.1 Update-1 to Sitecore 9.0 Update-2. After running the Update Installation Wizard I discovered that the order of most of the renderings on page items had changed in comparison to Sitecore 8.1. Beforehand we already tested an upgrade with Sitecore 9.0 Update-1 for this solution and it worked perfectly fine there. This implied that something must have changed between Sitecore 9 Update-1 and Update-2. After some time I found this helpful article in the Sitecore knowledge base which explains this behaviour (previously only covered Sitecore 8.2 Update-7). Turns out that Sitecore has changed the parsing logic of the layout information.
I checked the release dates of all the previous Sitecore versions and I think that you will run into this problem if you want to upgrade from one of the following versions:
- All versions prior to Sitecore 8.1
- Sitecore 8.1 Initial Release
- Sitecore 8.1 Update-1
In order to fix this problem you have to perform the following steps:
Update 15.02.2019: The gist has been updated due to a bug. The script automatically created an item version in the context language (most likely "en") when the shared layout field was modified.
- Backup the affected database(s)
- Install a clean instance of Sitecore 8.1 Update-2.
The easiest way to do this is to use SIM.
- Change the connection strings of your clean solution to point to the affected database(s).
- Copy the admin page below to your clean solution
- Change the setting Query.MaxItems to a high value which should be higher than the amount of page items you need to migrate (e.g. 10000)
- Run the script with the according parameters