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?

score 100 · Accepted Answer · edited Jun 18 '15 at 15:15

100

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.

edited Jun 18 '15 at 15:15

Marc Wittmann

2,286
2
28
41

answered Jun 18 '15 at 14:45

JonCole

2,902
1
17
19

3

thanks , this connection string worked for me 172.17.0.2:12000,abortConnect=false – Sagar Nov 08 '20 at 18:36
1

Very useful, thanks. Too bad the default setting is `true`. – Ceco Feb 02 '21 at 21:14
It may also be necessary to increase the default timeouts, e.g. `"Redis": "localhost,abortConnect=false,connectTimeout=30000,responseTimeout=30000"` – testpattern Oct 14 '21 at 13:11

score 21 · Answer 2 · edited Jun 28 '22 at 10:36

21

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);
}

edited Jun 28 '22 at 10:36

Masoud Keshavarz

2,166
9
36
48

answered May 01 '17 at 05:18

danigitman

730
8
11

1

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 Jun 20 '17 at 20:20
3

Found it, it's a ConfigurationOption of ConnectRetry set to the number of retries. Not sure what the default is set to. – Glenn Jun 20 '17 at 20:25
2

Default is 3 for ConnectRetry - https://stackexchange.github.io/StackExchange.Redis/Configuration.html – vshale Jan 12 '18 at 21:11

score 5 · Answer 3 · answered Nov 04 '16 at 10:48

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

score 2 · Answer 4 · answered May 15 '19 at 20:51

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.

score 2 · Answer 5 · answered Dec 29 '21 at 10:25

2

I fixed this by changing:

CacheSettings:ConnectionString=basketdb:6379

to

CacheSettings__ConnectionString=basketdb:6379

in the docker-compose.override.yml

answered Dec 29 '21 at 10:25

Afshin Ghazi

2,784
4
23
37

score 1 · Answer 6 · edited Aug 15 '18 at 12:08

1

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

edited Aug 15 '18 at 12:08

Rathma

1,196
2
33
65

answered Sep 26 '17 at 12:32

Roger Gusmao

3,788
1
20
17

score 0 · Answer 7 · answered Feb 24 '20 at 13:37

0

I fixed this by changing my connection string from localhost:6379 to 127.0.0.1:6379

answered Feb 24 '20 at 13:37

Markus

1,020
14
18

score 0 · Answer 8 · answered Aug 14 '20 at 03:51

0

For me, the connection string was incorrect. Adding the correct connection string details worked with stackexchange.redis 2.1.58

answered Aug 14 '20 at 03:51

Nilay

259
2
13

score 0 · Answer 9 · edited Aug 25 '23 at 08:05

0

You can use it this way.

public class RedisService
{
    private readonly string _host;
    private readonly int _port;
    private ConnectionMultiplexer _connectionMultiplexer;

    public RedisService(string host, int port)
    {
        _host = host;
        _port = port;
    }

    public void Connect() => _connectionMultiplexer = ConnectionMultiplexer.Connect($"{_host}:{_port}");
}

edited Aug 25 '23 at 08:05

Alexander Farber

21,519
75
241
416

answered Oct 30 '21 at 10:20

Veysel

1
1
1

2

Your answer could be improved with additional supporting information. Please [edit] to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers [in the help center](/help/how-to-answer). – Community Oct 30 '21 at 11:06

score 0 · Answer 10 · answered Feb 19 '22 at 04:04

0

Do ensure that you already have Redis set up. Here are instructions links for the respective OS:

Mac OS: https://gist.github.com/tomysmile/1b8a321e7c58499ef9f9441b2faa0aa8

Windows: https://dev.to/divshekhar/how-to-install-redis-on-windows-10-3e99

answered Feb 19 '22 at 04:04

Olanrewaju O. Joseph

848
10
13

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

10 Answers10

Linked