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The current pre-value collection is array based, use the PreValuesAsArray property instead

Upgrading from Umbraco 7.4.3 to 7.6.11 caused the following error to occur when I attempt to load the site:

The current pre-value collection is array based, use the PreValuesAsArray property instead. This usually indicates that the content cache is corrupt; the content cache has been rebuilt in an attempt to self-fix the issue.

How can I fix this error?

I have already tried republishing the site and checking the Data Integrity using the Health Check section.

Solution

  • This is likely a Property Value Converters error which is mentioned in the upgrade documentation.

    The site was not using the Models Builder as it was disabled in the Web.config using:

    <add key="Umbraco.ModelsBuilder.Enable" value="false" />

    In the umbracoSettings.config, the EnablePropertyValueConverters property was automatically added and set to true. Setting it to false fixed the error:

    <EnablePropertyValueConverters>true</EnablePropertyValueConverters>

    I believe the error occurs because this setting changes how the content cache XML is generated, so in order for the old code of the site to work, it needs to continue creating the XML in the same way.