When uptime kuma is down, tracking time is skipped

[MaddyGuthridge]

📑 I have found these related issues/pull requests

Had a quick search and could not find anything

🛡️ Security Policy

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

📝 Description

• When UptimeKuma is down, it obviously cannot record downtime.
• The problem is that when it starts up again, it does not display a gap in the measurements
• This causes it to falsely claim 100% uptime if it was not there to record the downtime

👟 Reproduction steps

1. Shut down UptimeKuma (in my case, my server unexpectedly shut down for about 5 hours while I was asleep)
2. Start it up again
3. Observe that no downtime is recorded.

👀 Expected behavior

UptimeKuma would list the times it could not perform the request as unrecorded (eg grey)

😓 Actual Behavior

UptimeKuma does not list the times at all, which causes the heartbeat to have inconsistent times.

🐻 Uptime-Kuma Version

2.0.2

💻 Operating System and Arch

Fedora Linux, running UptimeKuma in a Docker container

🌐 Browser

Firefox 145

🖥️ Deployment Environment

• Runtime Environment:
  • Docker: version 29.0.4, build 3247a5a
  • Docker Compose: version v2.40.3
• Database Storage:
  • Filesystem:
    • Linux: btrfs
  • Storage Medium: SSD/NVMe
• Uptime Kuma Setup:
  • Number of monitors: 28

📝 Relevant log output

uptime-kuma-1  | 2025-12-10T04:26:49+11:00 [MONITOR] WARN: Monitor #21 'GitLab': Under Maintenance | Type: http
uptime-kuma-1  | 2025-12-10T04:27:49+11:00 [MONITOR] WARN: Monitor #21 'GitLab': Under Maintenance | Type: http
uptime-kuma-1  | 2025-12-10T04:28:49+11:00 [MONITOR] WARN: Monitor #21 'GitLab': Under Maintenance | Type: http
uptime-kuma-1  | 2025-12-10T04:29:49+11:00 [MONITOR] WARN: Monitor #21 'GitLab': Under Maintenance | Type: http
uptime-kuma-1  | Welcome to Uptime Kuma
uptime-kuma-1  | Your Node.js version: 20.19.5
uptime-kuma-1  | 2025-12-10T02:16:18Z [SERVER] INFO: Env: production
uptime-kuma-1  | 2025-12-10T02:16:20Z [SERVER] INFO: Uptime Kuma Version: 2.0.2
uptime-kuma-1  | 2025-12-10T02:16:20Z [SERVER] INFO: Loading modules
uptime-kuma-1  | 2025-12-10T02:16:22Z [SERVER] INFO: Creating express and socket.io instance
uptime-kuma-1  | 2025-12-10T02:16:22Z [SERVER] INFO: Server Type: HTTP
uptime-kuma-1  | 2025-12-10T02:16:22Z [SERVER] INFO: Data Dir: ./data/
uptime-kuma-1  | 2025-12-10T02:16:22Z [DB] INFO: Database Type: sqlite
uptime-kuma-1  | 2025-12-10T02:16:22Z [SERVER] INFO: Connected to the database
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 48
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 47
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 46
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 44
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 45
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 42
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 43
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 41
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 40
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 39
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 38
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 37
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 36
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 35
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 34
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 33
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 32
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 31
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 30
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 29
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 28
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 27
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 26
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 25
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 24
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 23
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 22
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 21
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 20
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 19
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 18
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 15
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 14
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 13
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 12
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 11
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 10
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 9
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 8
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 7
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 6
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 5
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 4
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 3
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 2
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 51
uptime-kuma-1  | 2025-12-10T13:16:22+11:00 [MAINTENANCE] INFO: Generate cron for maintenance id: 50
uptime-kuma-1  | 2025-12-10T13:16:23+11:00 [SERVICES] INFO: Starting nscd
uptime-kuma-1  | 2025-12-10T13:16:23+11:00 [SERVER] INFO: Listening on 3001
uptime-kuma-1  | 2025-12-10T13:16:23+11:00 [MONITOR] WARN: Monitor #2 'Nextcloud site': Pending: Request failed with status code 502 | Max retries: 1 | Retry: 1 | Retry Interval: 60 seconds | Type: http

[CommanderStorm]

Claiming that the checks failed would be wrong as well...
Your monitoring infrastructure should not be impactable by the services you are monitoring going down so not tracking this at all seems reasonable.

You should add an external monitor if your uptime instance is up.

[cwchristerw]

I agree that it shouldn't show service status as down due to Uptime Kuma being down but instead it could show with grey status for the time Uptime Kuma was down.

[CommanderStorm]

This causes it to falsely claim 100% uptime if it was not there to record the downtime

I would not acount for it as downtime is what I am saying.

At least one gray check (or something like gray ... grey for longer times) is likely a good idea.
Harder to impelemnt under the current architecture though.

[MaddyGuthridge]

I sadly do not have the ability to run my uptime monitoring externally from my main site -- hosting off-premises is outside of my budget, and so in situations where my home loses electricity, both my server and my monitor go down. At the very least, I think that showing that the monitoring was unavailable would be a good idea.