If your app runs on an IPv4-only network, Supabase’s standard direct PostgreSQL connection may be unreachable: direct connections use IPv6 by default. The usual fix is to copy the project’s shared pooler connection string from Dashboard → Connect. Choose session mode for persistent connections or transaction mode for short-lived and serverless workloads. If you see the specific pooler error FATAL: (ENOTFOUND) tenant/user postgres.<project-ref> not found, check the copied pooler host and username before changing the database password.
Why can a Supabase connection string fail on IPv4?
Supabase’s standard direct database endpoint uses IPv6 by default. A deployment that supports only IPv4 cannot reach that endpoint unless the project has the IPv4 add-on enabled. For most IPv4-only deployments, the shared pooler is the practical alternative; Supabase documents its shared pooler as IPv4-compatible.
There are several connection choices, and they are not interchangeable:
| Option | Endpoint and address family | Best fit | Limitation |
|---|---|---|---|
| Direct connection | Port 5432; IPv6 by default | Persistent backends that support IPv6, or direct connections after enabling the IPv4 add-on | An IPv4-only host cannot reach the standard endpoint without the add-on. |
| Shared pooler, session mode | IPv4; port 5432 | Persistent sessions and third-party database tools, including from IPv4-only networks | Use the project-specific host and include the project reference in the shared-pooler username. |
| Shared pooler, transaction mode | IPv4; port 6543 | Serverless, edge functions, and other short-lived connection patterns | Does not support prepared statements or query pipelining. |
| IPv4 add-on | Enables IPv4 reachability for the direct connection | When direct connectivity or a dedicated IPv4 ingress address is required | It is an optional paid add-on; availability and terms should be checked in the project dashboard. |
| Supabase client libraries or Data APIs | IPv4-compatible APIs | Frontend use cases that do not require a raw PostgreSQL connection | Frontend data access should be protected with Row Level Security and appropriate policies. |
Connection modes and endpoint behavior are described in Supabase’s PostgreSQL connection documentation and its IPv4 address documentation.
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How do you fix Supabase ENOTFOUND?
First distinguish the specific shared-pooler error FATAL: (ENOTFOUND) tenant/user postgres.<project-ref> not found from a generic DNS or application error that happens to contain “ENOTFOUND.” Supabase documents this exact tenant/user message as a pooler lookup failure. For that error, a host or username mismatch is more likely than a bad password.
- Open the project’s Connect dialog. In the Supabase Dashboard, select Connect, then choose Session pooler or Transaction pooler to match the workload.
- Copy the full displayed connection string. Do not assemble the pooler hostname from the project’s region or guess a cluster such as
aws-0. The host includes a pooler cluster index, and the correct value is project-specific. Supabase’s pooler troubleshooting guidance recommends using the actual displayed host. - Check that the username matches the shared pooler. It normally has the form
postgres.[PROJECT-REF]. A custom role uses[ROLE].[PROJECT-REF]. Using onlypostgresomits the project reference required for the shared pooler. - Check the port against the selected mode. Shared session mode uses port
5432; shared transaction mode uses port6543. Keep the username and port paired with the mode shown in Connect. - Replace only the password placeholder. Supabase’s documentation says to “Copy the whole string, and replace only the password placeholder.” If the password contains reserved characters such as
&,#,?, or spaces, percent-encode them for the URL-style connection string.
Because the documented tenant/user failure usually points to the host or username, resetting the password should not be the first troubleshooting step. See Supabase’s guidance for the tenant/user ENOTFOUND error.
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Should you use session mode or transaction mode?
Choose session mode for persistent connections
Session pooling is designed for a connection pattern that needs a persistent session. It is also a shared-pooler option for third-party database tools. Its port is 5432. The exact endpoint and username still need to come from that project’s Connect dialog.
Choose transaction mode for short-lived workloads
Transaction pooling assigns a database backend for the duration of a transaction rather than preserving a backend for a client session. That makes it suitable for serverless and other short-lived connection patterns, but it is not a sticky session. Applications that rely on session state or unsupported features should use session mode or direct connectivity instead.
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Transaction mode does not support prepared statements or query pipelining. If a driver enables prepared statements, disable that behavior when using transaction mode; confirm the driver’s settings rather than assuming it is compatible by default. Supabase lists these constraints in its connection-mode documentation.
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When should you enable the IPv4 add-on?
Use the IPv4 add-on when the application specifically requires a direct database connection or a dedicated IPv4 ingress address. It is optional and paid, and its current availability and terms can change, so check the project dashboard rather than relying on a price or availability claim from elsewhere.
Enabling the add-on is not the same as making the endpoint dual-stack: Supabase says it swaps the project’s IPv6 AAAA DNS record for an IPv4 A record. That means the endpoint becomes reachable over IPv4 only, so verify the effect on your expected clients before enabling it. See Supabase’s IPv4 add-on documentation.
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How can you confirm whether the deployment supports IPv6?
If you want to keep direct mode, test from the deployment server rather than from a laptop on a different network. Supabase documents this command:
curl -6 https://ifconfig.co/ipA returned IPv6 address indicates IPv6 compatibility from that server. If the command cannot return an address, use the shared pooler for an IPv4-only runtime or assess whether the IPv4 add-on meets the project’s direct-connection needs. The check and its interpretation are covered in Supabase’s IPv4 address guide.
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- Marvelous Durability: Internet cable wrapped with quality cotton braided cord, which makes the LAN cable stronger and more durable. The test proves that this internet cable can be bent at least 10000 times without broken, very suitable for long-term use
- PoE Supported: All lengths of ethernet cord can support the PoE power supply function except 65ft. You don't need additional power supply when installing a PoE camera, which is very convenient and safe
- Wide Compatibility: With the RJ45 Connector, network cable can be perfectly compatible with computers, laptops, modems, routers, PS5, X-Box and other networking devices. It can also be fully backward compatible with Cat7, Cat6e, Cat6, Cat5e, Cat5
What if ENOTFOUND is not the pooler tenant/user error?
The host-and-username fix applies to the precise message FATAL: (ENOTFOUND) tenant/user postgres.<project-ref> not found. A different ENOTFOUND may instead be a DNS resolution failure or an application-specific issue, so do not assume the pooler username is at fault. Compare the full error text, confirm which endpoint your runtime is using, and use the project’s Connect dialog for current host details.
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