2 months ago
hi
I keep getting error in connecting to my mongoDB cluster from NodeJS server.
it used to work well for 2 years, and with nothing changed it started failing almost all the time, making my service unavailable
error:
[MongoDB] Connection failed: MongoServerSelectionError: getaddrinfo ENOTFOUND ac-olibm3r-shard-00-00.cuhp6kd.mongodb.net
at Topology.selectServer (/app/node_modules/mongodb/src/sdam/topology.ts:624:30)
at async Topology._connect (/app/node_modules/mongodb/src/sdam/topology.ts:470:22)
at async Topology.connect (/app/node_modules/mongodb/src/sdam/topology.ts:407:7)
at async topologyConnect (/app/node_modules/mongodb/src/mongo_client.ts:610:9)
at async MongoClient._connect (/app/node_modules/mongodb/src/mongo_client.ts:622:7)
at async MongoClient.connect (/app/node_modules/mongodb/src/mongo_client.ts:534:7) {
reason: TopologyDescription {
type: 'ReplicaSetNoPrimary',
It is pure DNS resolution failure from Railway → MongoDB Atlas
11 Replies
2 months ago
Your service logs show repeated ENOTFOUND errors for ac-olibm3r-shard-00-00.cuhp6kd.mongodb.net, which is a DNS resolution failure. We traced the DNS chain for that hostname and it ultimately resolves to an AWS EC2 address that returns no A/AAAA records from the public internet, meaning the issue is with your MongoDB Atlas cluster's DNS, not with our platform. We recommend checking the status of your cluster in the MongoDB Atlas dashboard to ensure it hasn't been paused, terminated, or migrated to a new hostname.
Status changed to Awaiting User Response Railway • 2 months ago
Status changed to Awaiting Railway Response Railway • 2 months ago
2 months ago
my cluster is working fine, and connecting to it from my PC works well
guyyt
my cluster is working fine, and connecting to it from my PC works well
2 months ago
this call from Nodejs server deployed to Railway is not working from my project:
Railway
Your service logs show repeated `ENOTFOUND` errors for `ac-olibm3r-shard-00-00.cuhp6kd.mongodb.net`, which is a DNS resolution failure. We traced the DNS chain for that hostname and it ultimately resolves to an AWS EC2 address that returns no A/AAAA records from the public internet, meaning the issue is with your MongoDB Atlas cluster's DNS, not with our platform. We recommend checking the status of your cluster in the MongoDB Atlas dashboard to ensure it hasn't been paused, terminated, or migrated to a new hostname.
2 months ago
Hello,
I’m experiencing the same issue. DNS resolution is failing (ENOTFOUND) for ac-mvn5kly-shard-00-0{0,1,2}.pgawsr9.mongodb.net, specifically ac-mvn5kly-shard-00-00.pgawsr9.mongodb.net.
I’m able to access the cluster locally, via MongoDB Compass, and directly through MongoDB without any problems. The DNS issue only occurs on Railway. Could you please advise?
2 months ago
I will mention that now its working again
but this is not the first time its happening, and its crashing our service
and it would probably happen again
Status changed to Solved jake • 2 months ago
2 months ago
sorry this is not solved
how can we make sure it does not happen again?
Status changed to Awaiting Railway Response Railway • 2 months ago
Status changed to Open Railway • 2 months ago
2 months ago
Hello, so the dns for your cluster returns zero records from the public internet, meaning the issue is definitely on atlas's side not railway's. just log into your mongodb atlas dashboard and check if your cluster is paused, terminated, or got a new hostname, one of those three is almost certainly the culprit. resume it if paused and you should be good
2 months ago
one thing to note since it fails "almost all the time" and not always, your cluster isn't fully terminated, something still responds occasionally. so just check your atlas dashboard for a paused cluster or a hostname change, one of those two is your issue
Hope this help you :)
domehane
one thing to note since it fails "almost all the time" and not always, your cluster isn't fully terminated, something still responds occasionally. so just check your atlas dashboard for a paused cluster or a hostname change, one of those two is your issue Hope this help you :)
2 months ago
its probably not Atlas, since on local PC my server connecter to Mongo without problems
2 months ago
During debugging, I observed that the DNS resolution chain points to an AWS instance in the me-south-1 (Middle East – Bahrain) region, which is currently experiencing infrastructure issues. These appear to be caused by underlying AWS failures rather than MongoDB itself.
As a result, shards hosted in this region, such as ac-mvn5kly-shard-00-00.pgawsr9.mongodb.net may become unreachable or unstable.
AWS outages are often region or Availability Zone–specific, and MongoDB Atlas nodes are physically tied to those regions. Because of this, different clients (e.g., local environments vs. Railway) may:
- Resolve to different DNS endpoints
- Route through different network paths
- Connect to different IPs or replicas
This explains why:
- A local machine may connect via a healthy path or replica
- Railway may route to an affected zone or failing node
Access to a MongoDB shard can vary depending on the client’s region and network path. During regional AWS outages (such as in me-south-1), some environments may fail to resolve or reach the shard, while others may continue to work.
From my understanding, it depends on AWS regional availability. I would appreciate any advice or recommendations on how to avoid this in the future.
I hope this helps
2 months ago
please note the same is happening now