Description

After March 31, 2020, Microsoft Azure will only support TLS1.2 for Azure Redis Cache and will stop supporting TLS1.0 and TLS1.1. Sitecore XP 8.x on .NET 4.6.1 and lower will not be able to connect and work with Redis Cache using TLS 1.0 or TLS 1.1.

For more details, have a look at https://docs.microsoft.com/en-us/azure/azure-cache-for-redis/cache-remove-tls-10-11.

You may also be interested in the following article: Authentication issues with TLS 1.0 on Azure App Services.

Solution

To resolve the issue, consider one of the following options:

• Upgrade your instance to SC XP 9.0 Initial Release or higher.
  Higher Sitecore versions target higher framework versions that use TLS 1.2 by default.
• Upgrade the StackExchange.Redis.StrongName.dll V1.0.488 to StackExchange.Redis.StrongName.dll V1.2.6 as defined below.
  
  1. Download StackExchange.Redis.StrongName Version 1.2.6 from https://www.nuget.org/packages/StackExchange.Redis.StrongName/
  2. Open the downloaded package and find StackExchange.Redis.StrongName.dll in the net45 folder.
  3. Replace the existing StackExchange.Redis.StrongName.dll with the downloaded one under the instance bin folder.
  4. Add binding redirect to the Web.config file:
     

     <dependentAssembly>
        <assemblyIdentity name="StackExchange.Redis.StrongName" publicKeyToken="c219ff1ca8c2ce46" xmlns="urn:schemas-microsoft-com:asm.v1" />
        <bindingRedirect oldVersion="1.0.0.0-1.2.6.0" newVersion="1.2.6.0" xmlns="urn:schemas-microsoft-com:asm.v1" />
     </dependentAssembly>

  5. Update a connection string to the Redis cache with additional parameter SslProtocols=Tls12, e.g:
     

     <add name="redis.sessions" connectionString=your-redis-prefix.redis.cache.windows.net:6380,password=your-redis-password=,ssl=True,abortConnect=False,SslProtocols=Tls12" />

  6. Restart the Sitecore instance.