Quick answer
MySQL documents simultaneous client connections as 151 default; configurable 1–100,000. The effective maximum is also constrained by open_files_limit.
Verified Aug 22, 2026Official source
Current limits
| Constraint | Current value | Scope | Verified source |
|---|---|---|---|
| simultaneous client connectionsThe effective maximum is also constrained by open_files_limit. | 151 default; configurable 1–100,000 | MySQL 8.4 server | OracleAug 22, 2026 |
Why does this limit matter?
Raising max_connections without memory and file-descriptor planning can trade rejection for instability.
This value is scoped to MySQL 8.4 server; a different plan, runtime, model, endpoint, region, or account can produce a different effective constraint.
What should you check?
- Run SHOW VARIABLES LIKE 'max_connections' and inspect open_files_limit plus current sessions.
- Confirm the exact plan, model, runtime, endpoint, region, and account that serve the failing workload.
- Record the observed value, response headers or configuration, timestamp, and source without logging secrets.
Important caveats
- Managed providers can set a lower range or derive the value from instance size.
- Treat the official source and live account configuration as authoritative if they differ from this verified snapshot.
HyperObserve reports the documented platform constraint. Your application, SDK, gateway, provider, region, or account can impose a lower effective limit.
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