Kentico 9 Sudden Malfunction

Fuad Dahlan asked on June 1, 2018 05:33

Hi, recently I try to run the website and I got this message "CS1660: Cannot convert lambda expression to type 'System.Collections.Generic.IEqualityComparer

Correct Answer

Juraj Ondrus answered on August 7, 2018 15:51

The issue is described in this KB Article

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Recent Answers

Michal Samuhel answered on June 1, 2018 07:47 (last edited on June 1, 2018 07:48)

Hi Fuad,

This happens due to windows and .NET update where microsoft added a method with same signature as the one we had already created within our API. The solution:

Upgrade to v10 or higher

Roll back the Windows update

Use web application project

Change code in \CMS\App_Code\CMS\UpgradeProcedure.cs: From: .ToDictionary(group => group.Key, group => group.Select(u => u.Email).ToHashSet(StringComparer.InvariantCultureIgnoreCase));

To: .ToDictionary(group => group.Key, group => CMS.DataEngine.DataExtensions.ToHashSet(group.Select(u => u.Email), StringComparer.InvariantCultureIgnoreCase));

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Iain Waddell answered on August 21, 2018 17:03 (last edited on August 21, 2018 17:05)

Do you have details about the .NET update that causes the problem?

Just hit the problem on my development machine and the code change worked, but would be handy to know which update caused the problem.

Edit: Just seen the KB link on the page, so please ignore.

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Brett Andrew answered on November 8, 2018 06:36

We encountered this in Production in Azure today, Microsoft must have updated their services and all at once all environments including Production went down.

We had to rename the offending file wwwroot\App_Code\CMS\UpgradeProcedure.cs to wwwroot\App_Code\CMS\UpgradeProcedure.cs.broken

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Juraj Ondrus answered on November 8, 2018 06:48

Hi Brett,
You can follow the article mentioned above to fix the issue. Also, Microsoft announced that the .Net version will be changed back in April and the release was also postponed in August.

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