certificateValidationMode None not working

I have a problem with our dev environment. We make use of a self certificate what results in the error:

Microsoft.SharePoint.SPImmutableCertificateValidator.Validate(X509Certificate2 certificate) +1274

so what i would like to do is to turn off the validation in our environment. I did find the following fix:

<authentication certificateValidationMode="None" />

it doesn't seem to work.

here is a sample of a part of the web.config

<microsoft.identityModel><service saveBootstrapTokens="true"><audienceUris /><issuerNameRegistry type="Microsoft.SharePoint.IdentityModel.SPPassiveIssuerNameRegistry, Microsoft.SharePoint, Version=15.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" /><issuerTokenResolver type="Microsoft.SharePoint.IdentityModel.SPIssuerTokenResolver, Microsoft.SharePoint.IdentityModel, Version=15.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" /><securityTokenHandlers><clear /><add type="Microsoft.IdentityModel.Tokens.X509SecurityTokenHandler, Microsoft.IdentityModel, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" /><add type="Microsoft.SharePoint.IdentityModel.SPSaml11SecurityTokenHandler, Microsoft.SharePoint.IdentityModel, Version=15.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c"><samlSecurityTokenRequirement><nameClaimType value="http://schemas.microsoft.com/sharepoint/2009/08/claims/userid" /></samlSecurityTokenRequirement></add><add type="Microsoft.SharePoint.IdentityModel.SPTokenCache, Microsoft.SharePoint.IdentityModel, Version=15.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" /></securityTokenHandlers><federatedAuthentication><wsFederation passiveRedirectEnabled="false" issuer="https://none" realm="https://none" /><cookieHandler mode="Custom" path="/"><customCookieHandler type="Microsoft.SharePoint.IdentityModel.SPChunkedCookieHandler, Microsoft.SharePoint.IdentityModel, Version=15.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" /></cookieHandler></federatedAuthentication><certificateValidation certificateValidationMode="None" /></service>