RedisTimeoutException is crashing my aspnet core application

I agree with @thepirat000's answer, reason is ConnectionMultiplexer

You can use ConnectionMultiplexer according your Redis package (StackExchange.Redis or ServiceStack.Redis) and according your deployment environment

In my aspnet core application (like you) i have used StackExchange.Redis and i have deployed to windows server without any error within below Startup.cs settings

        #region Redis settings ConnectionMultiplexer
        services.AddDataProtection().ProtectKeysWithDpapi(protectToLocalMachine: true);
        services.AddDataProtection()
            .PersistKeysToFileSystem(new DirectoryInfo(@"c:\temp-keys"))
            .ProtectKeysWithDpapiNG($"CERTIFICATE=HashId:{thumbPrint}", flags: Microsoft.AspNetCore.DataProtection.XmlEncryption.DpapiNGProtectionDescriptorFlags.None);
        services.AddDataProtection().ProtectKeysWithDpapiNG();

        services.Configure<StorageConfiguration>(new ConfigurationBuilder().SetBasePath(Directory.GetCurrentDirectory()).AddJsonFile("appsettings.json", optional: true, reloadOnChange: true).Build());
        var redisConf = Configuration.GetSection("RedisConnection").Get<RedisConnection>();
        ConnectionMultiplexer redis = ConnectionMultiplexer.Connect(redisConf.Host.ToString() + ":" + redisConf.Port.ToString());
        services.AddDataProtection().PersistKeysToStackExchangeRedis(redis, "DataProtection-Keys");
        services.AddSingleton<IConnectionMultiplexer>(ConnectionMultiplexer.Connect(redisConf.Host.ToString() + ":" + redisConf.Port.ToString()));
        #endregion

Look here for basic usage https://stackexchange.github.io/StackExchange.Redis/Basics.html

How are you creating the ConnectionMultiplexer instances?

Maybe you are not reusing a multiplexer instance and creating a lot of connections.

The ConnectionMultiplexer object should be shared and reused between callers. It is not recommended to create a ConnectionMultiplexer per operation. Check StackExchange.Redis documentation here for more information.

About the exception handling on Asp.NET Core, you can use the UseExceptionHandler diagnostic middleware to handle exceptions globally. Check this article for a complete explanation

Have you tried to put the block that throws the exception in a try/catch block? And perhaps make it try a few times with Polly when there is a timeout. https://github.com/App-vNext/Polly

Normally it shouldn't terminate your app, but since you didn't share any code, We can not be sure.

If you create a service class like below, you can encapsulate all of your redis calls, therefore catch the exceptions.

public class EmptyClass
{
    private readonly ConnectionMultiplexer _connectionMultiplexer;

    public EmptyClass(ConnectionMultiplexer connectionMultiplexer)
    {
        _connectionMultiplexer = connectionMultiplexer;
    }

    public void Execute(Action<ConnectionMultiplexer> action)
    {
        try
        {
            action.Invoke(_connectionMultiplexer);
        }
        catch(RedisTimeoutException ex)
        {

        }
    }

    public void TestRun()
    {
        Execute((ConnectionMultiplexer obj) =>
        {
            //do stuff with obj.
        });
    }
}