Trace: KnexTimeoutError: Knex: Timeout acquiring a connection. The pool is probably full. Are you missing a .transacting(trx) call?

[jakeaturner]

📑 I have found these related issues/pull requests

Possibly related to #6331 and #6166 , but those seem to be related to acquiring a database connection in general, not pooling issues

🛡️ Security Policy

• I have read and agree to Uptime Kuma's Security Policy.

📝 Description

Hello,

We upgraded to v2 about 8 weeks ago and since then, about once or twice a week all of our monitors will start cascading with DOWN reports and the message Trace: KnexTimeoutError: Knex: Timeout acquiring a connection. The pool is probably full. Are you missing a .transacting(trx) call?. After a minute or two, they all start coming back UP.

Again, it's not constant nor predictable, just randomly seems to happen. Though, it does seem to be occuring a little more frequently the longer we've been running v2. We do have quite a few monitors (~124) so wondering if it's some kind of leaky connection or missing transaction flush?

Thanks so much for any help you can provide

👟 Reproduction steps

A bit difficult to reproduce since it doesn't seem to be tied to any specific action. We just have to wait until it springs up again 🤷‍♂️

👀 Expected behavior

Monitors will not report DOWN if this happens

😓 Actual Behavior

All monitors report DOWN and then come back UP after a few minutes

🐻 Uptime-Kuma Version

2.0.0

💻 Operating System and Arch

Ubuntu Server LTS 22.10

🌐 Browser

Google Chrome Version 143.0.7499.42 (Official Build) (64-bit)

🖥️ Deployment Environment

• Runtime Environment:
  • Docker: Version 24.0.5, build ced0996
  • Docker Compose: Version 2.20.2
  • Portainer (BE/CE): N/A
  • MariaDB: N/A
  • Node.js: N/A (Docker)
  • Kubernetes: N/A
• Database:
  • SQLite: Embedded
• Database Storage:
  • Filesystem:
    • Linux: ext4
  • Storage Medium: SSD
• Uptime Kuma Setup:
  • Number of monitors: 124

📝 Relevant log output

2025-12-12T13:15:48-08:00 [MONITOR] ERROR: Please report to https://github.com/louislam/uptime-kuma/issues
2025-12-12T13:15:48-08:00 [MONITOR] INFO: Try to restart the monitor
Trace: KnexTimeoutError: Knex: Timeout acquiring a connection. The pool is probably full. Are you missing a .transacting(trx) call?
    at Client_SQLite3.acquireConnection (/app/node_modules/knex/lib/client.js:332:26)
    at runNextTicks (node:internal/process/task_queues:60:5)
    at process.processTimers (node:internal/timers:516:9)
    at async Runner.ensureConnection (/app/node_modules/knex/lib/execution/runner.js:305:28)
    at async Runner.run (/app/node_modules/knex/lib/execution/runner.js:30:19)
    at async RedBeanNode.storeCore (/app/node_modules/redbean-node/dist/redbean-node.js:141:17)
    at async RedBeanNode.store (/app/node_modules/redbean-node/dist/redbean-node.js:110:20)
    at async UptimeCalculator.update (/app/server/uptime-calculator.js:309:9)
    at async beat (/app/server/model/monitor.js:979:32)
    at async Timeout.safeBeat [as _onTimeout] (/app/server/model/monitor.js:1019:17) {
  sql: undefined,
  bindings: undefined
}
    at Timeout.safeBeat [as _onTimeout] (/app/server/model/monitor.js:1021:25)
    at runNextTicks (node:internal/process/task_queues:60:5)
    at process.processTimers (node:internal/timers:516:9)
2025-12-12T13:15:48-08:00 [MONITOR] ERROR: Please report to https://github.com/louislam/uptime-kuma/issues
2025-12-12T13:15:48-08:00 [MONITOR] INFO: Try to restart the monitor
Trace: KnexTimeoutError: Knex: Timeout acquiring a connection. The pool is probably full. Are you missing a .transacting(trx) call?
    at Client_SQLite3.acquireConnection (/app/node_modules/knex/lib/client.js:332:26)
    at async Runner.ensureConnection (/app/node_modules/knex/lib/execution/runner.js:305:28)
    at async Runner.run (/app/node_modules/knex/lib/execution/runner.js:30:19)
    at async RedBeanNode.storeCore (/app/node_modules/redbean-node/dist/redbean-node.js:141:17)
    at async RedBeanNode.store (/app/node_modules/redbean-node/dist/redbean-node.js:110:20)
    at async UptimeCalculator.update (/app/server/uptime-calculator.js:309:9)
    at async beat (/app/server/model/monitor.js:979:32)
    at async Timeout.safeBeat [as _onTimeout] (/app/server/model/monitor.js:1019:17) {
  sql: undefined,
  bindings: undefined
}
    at Timeout.safeBeat [as _onTimeout] (/app/server/model/monitor.js:1021:25)
2025-12-12T13:15:48-08:00 [MONITOR] ERROR: Please report to https://github.com/louislam/uptime-kuma/issues
2025-12-12T13:15:49-08:00 [MONITOR] INFO: Try to restart the monitor
2025-12-12T13:17:40-08:00 [MONITOR] ERROR: Cannot send notification to Email Alert Service
2025-12-12T13:17:41-08:00 [MONITOR] ERROR: Error: write EPIPE
    at afterWriteDispatched (node:internal/stream_base_commons:161:15)
    at writeGeneric (node:internal/stream_base_commons:152:3)
    at Socket._writeGeneric (node:net:958:11)
    at Socket._write (node:net:970:8)
    at writeOrBuffer (node:internal/streams/writable:572:12)
    at _write (node:internal/streams/writable:501:10)
    at Writable.write (node:internal/streams/writable:510:10)
    at SMTPConnection._sendCommand (/app/node_modules/nodemailer/lib/smtp-connection/index.js:1023:22)
    at SMTPConnection._actionEHLO (/app/node_modules/nodemailer/lib/smtp-connection/index.js:1301:18)
    at SMTPConnection._processResponse (/app/node_modules/nodemailer/lib/smtp-connection/index.js:991:20) {
  errno: -32,
  code: 'ESOCKET',
  syscall: 'write',
  command: 'CONN'
}
2025-12-12T13:17:46-08:00 [MONITOR] WARN: Monitor #99 '[redacted]': Failing: Knex: Timeout acquiring a connection. The pool is probably full. Are you missing a .transacting(trx) call? | Interval: 120 seconds | Type: http | Down Count: 0 | Resend Interval: 0
Trace: KnexTimeoutError: Knex: Timeout acquiring a connection. The pool is probably full. Are you missing a .transacting(trx) call?
    at Client_SQLite3.acquireConnection (/app/node_modules/knex/lib/client.js:332:26)
    at async Runner.ensureConnection (/app/node_modules/knex/lib/execution/runner.js:305:28)
    at async Runner.run (/app/node_modules/knex/lib/execution/runner.js:30:19)
    at async RedBeanNode.storeCore (/app/node_modules/redbean-node/dist/redbean-node.js:150:26)
    at async RedBeanNode.store (/app/node_modules/redbean-node/dist/redbean-node.js:110:20)
    at async beat (/app/server/model/monitor.js:989:13)
    at async Timeout.safeBeat [as _onTimeout] (/app/server/model/monitor.js:1019:17) {
  sql: undefined,
  bindings: undefined
}
    at Timeout.safeBeat [as _onTimeout] (/app/server/model/monitor.js:1021:25)
2025-12-12T13:18:17-08:00 [MONITOR] ERROR: Please report to https://github.com/louislam/uptime-kuma/issues
2025-12-12T13:18:17-08:00 [MONITOR] INFO: Try to restart the monitor