It was not possible to connect to the redis server(s); to create a disconnected multiplexer

Question

I have the following piece of code to connect to azure redis cache.

   public class CacheConnectionHelper
    {
        private static Lazy<ConnectionMultiplexer> lazyConnection = new Lazy<ConnectionMultiplexer>(() =>
        {
            return ConnectionMultiplexer.Connect(SettingsHelper.AzureRedisCache);
        });

        public static ConnectionMultiplexer Connection
        {
            get
            {
                return lazyConnection.Value;
            }
        }
    }

And I use it this way

public static List<Models.Module> GetModules()
        {
            IDatabase cache = CacheConnectionHelper.Connection.GetDatabase();
            List<Models.Module> listOfModules = new List<Models.Module>();
            listOfModules = (List<Models.Module>)cache.Get("ApplicationModules");
            if (listOfModules == null)
            {
                listOfModules = dbApp.Modulos.ToList();
                cache.Set("ApplicationModules", listOfModules, TimeSpan.FromMinutes(SettingsHelper.CacheModuleNames));
                return listOfModules;
            }
            else {
                return listOfModules;
            }
        }

However 1 or 2 times per day I get this exception:

Additional information: It was not possible to connect to the redis server(s); to create a disconnected multiplexer, disable AbortOnConnectFail. UnableToResolvePhysicalConnection on PING

The question is how can I refactor this code to go to the database in case the cache connection fails?

Solution 1

The error you are getting is usually a sign that you have not set abortConnect=false in your connection string. The default value for abortConnect is true, which makes it so that StackExchange.Redis won't reconnect to the server automatically under some conditions. We strongly recommend that you set abortConnect=false in your connection string so that SE.Redis will auto-reconnect in the background if a network blip occurs.

Solution 2

for beginners who dive in other's code an face this problem:

if (RedisConn == null)
        { 
            ConfigurationOptions option = new ConfigurationOptions
            {
                AbortOnConnectFail = false,
                EndPoints = { redisEndpoint }
            };
            RedisConn = ConnectionMultiplexer.Connect(option);
        }

Solution 3

You should also pay attention to the last part of your error message, as it seems to provide very useful details about the reason why connection have failed.

In your case:

It was not possible to connect to the redis server(s); to create a disconnected multiplexer, disable AbortOnConnectFail. UnableToResolvePhysicalConnection on PING

My case:

It was not possible to connect to the redis server(s); to create a disconnected multiplexer, disable AbortOnConnectFail. Timeout

Solution 4

This problem was solved in a new release, the version 1.2.6 - you can see in Here

Solution 5

For those maintaining older codebases, you may run into "It was not possible to connect to the redis server(s); to create a disconnected multiplexer, disable AbortOnConnectFail. UnableToResolvePhysicalConnection on PING"

Once I upgraded to a more recent nuget package the error was still present but I got more error information: "The client and server cannot communicate, because they do not possess a common algorithm".

Once I applied the registry keys mentioned here I was ok. For those that don't wish to make that global change I believe there has been a PR for a setting.

View more solutions

Comments

[Glenn]

Perfect... but what is the failsafe? If it fails on the first network blip we are ok with letting it try again but not indefinitely. Are there additional options? Google pointed me here.

[Glenn]

Found it, it's a ConfigurationOption of ConnectRetry set to the number of retries. Not sure what the default is set to.

[vshale]

Default is 3 for ConnectRetry - stackexchange.github.io/StackExchange.Redis/Configuration.ht‌​ml

[Sagar]

thanks , this connection string worked for me 172.17.0.2:12000,abortConnect=false

[Ceco]

Very useful, thanks. Too bad the default setting is true.

[testpattern]

It may also be necessary to increase the default timeouts, e.g. "Redis": "localhost,abortConnect=false,connectTimeout=30000,responseT‌​imeout=30000"

[Admin]

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