Azure Redis Cache – “No endpoints specified” Error (In dotnet core)

services.AddDistributedRedisCache(option =>
{
    option.Configuration = String.Format(
        Configuration.GetConnectionString("RedisCache"),
        Configuration.GetValue("RedisPassword"));
    option.InstanceName = Configuration.GetValue("RedisCacheInstance");
});

services.AddStackExchangeRedisCache(option =>
{
    option.Configuration = String.Format(
        Configuration.GetConnectionString("RedisCache"),
        Configuration.GetValue("RedisPassword"));
    option.InstanceName = Configuration.GetValue("RedisCacheInstance");
});

When trying to use this I get a big exception which tells me “No Endpoints Specified” which is weird, because the connection string is correct and it, by definition, specifies the endpoint to connect to.

I was even following this great tutorial by Tobias Zimmergren to make sure I wasn’t doing something stupid. But it seems at some point there’s been a bug/feature introduced that means you can’t specify the connection string, and then add some other options. It’s now a “one or the other” setup… but there’s no explanation of that’s what the problem is, or even a hint as to that’s what’s wrong.

I was able to find the error here in the StackExchange.Redis source code and it seems that the configuration is either one or the other. You can’t mix and match any more.

internal static ConfigurationOptions PrepareConfig(object configuration)
{
    if (configuration == null) throw new ArgumentNullException(nameof(configuration));
    ConfigurationOptions config;
    if (configuration is string s)
    {
        config = ConfigurationOptions.Parse(s);
    }
    else if (configuration is ConfigurationOptions configurationOptions)
    {
        config = (configurationOptions).Clone();
    }
    else
    {
        throw new ArgumentException("Invalid configuration object", nameof(configuration));
    }
    if (config.EndPoints.Count == 0) throw new ArgumentException("No endpoints specified", nameof(configuration));
    config.SetDefaultPorts();
    return config;
}

So now, to get the redis cache working you need to break your connection string apart and specify your options manually, and get rid of your connection string.

Now my setup in startup.cs looks like this:

And everything seems to be working fine (I’ve added some retry options in there as well now.

So in part… when upgrading your Redis IDistributed Cache in dotnet core…. you can’t mix connection strings and connection options. You have to use one or the other.

Hopefully this post will help someone else find a solution quicker than I did, as I couldn’t find an explanation anywhere.

Peace.