[bug] std::regex abort

[georglauterbach]

Describe the bug
The first time waybar launches, it freezes. Then it is restarted and it works

To reproduce
I though it had something to do with the Wireplumber module (see #4584 (comment)), but @Alexays noted that my issue is separate from #4584.

Click to expand Waybar configuration...

{
  "layer": "top",
  "position": "top",
  "spacing": 5,
  "reload_style_on_change": true,
  "modules-left": [
    "tray",
    "idle_inhibitor",
    "custom/audio_idle_inhibitor",
    "custom/notifications",
    "sway/window",
    "sway/mode"
  ],
  "modules-center": [
    "sway/workspaces"
  ],
  "modules-right": [
    //"custom/gpu",
    "cpu",
    "memory",
    "network",
    "wireplumber",
    "wireplumber#source",
    //"battery",
    "clock"
  ],
  // -------------------------------------------
  // ----  Left Modules  -----------------------
  // -------------------------------------------
  "tray": {
    "icon-size": 15,
    "show-passive-items": true
  },
  "idle_inhibitor": {
    "format": "{icon}",
    "format-icons": {
      "activated": " ",
      "deactivated": " "
    },
    "tooltip-format-activated": "idle inhibitor {status}",
    "tooltip-format-deactivated": "idle inhibitor {status}",
    "timeout": 180
  },
  "custom/audio_idle_inhibitor": {
    "exec": "sway-audio-idle-inhibit --dry-print-both-waybar",
    "return-type": "json",
    "format": "{icon}",
    "format-icons": {
      "output": "  ",
      "input": "  ",
      "output-input": "  ",
      "none": "  "
    },
    "tooltip": false
  },
  "custom/notifications": {
    "exec": "swaync-client --subscribe-waybar",
    "return-type": "json",
    "escape": true,
    "format": "{icon} {text:>2}",
    "format-icons": {
      "notification": " ",
      "none": " ",
      "dnd-notification": " ",
      "dnd-none": " ",
      "inhibited-notification": "󱅫 ",
      "inhibited-none": "󱅫 ",
      "dnd-inhibited-notification": " ",
      "dnd-inhibited-none": " "
    },
    "tooltip": false,
    "on-click": "swaync-client --toggle-panel --skip-wait",
    "on-click-right": "swaync-client --toggle-dnd --skip-wait"
  },
  "sway/window": {
    "max-length": 90,
    "swap-icon-label": false
  },
  // -------------------------------------------
  // ----  Middle Modules  ---------------------
  // -------------------------------------------
  "sway/workspaces": {
    "format": "{name}",
    "all-outputs": false,
    "disable-scroll": true,
    "sort-by-number": true
  },
  // -------------------------------------------
  // ----  Right Modules  ----------------------
  // -------------------------------------------
  "cpu": {
    "interval": 5,
    "format": " {usage:3}%"
  },
  "custom/gpu": {
    "exec-if": "which gpu-usage-waybar",
    "exec": "gpu-usage-waybar --interval 5000",
    "return-type": "json",
    "format": "󰍹 {:>9}",
    "tooltip": true
  },
  "memory": {
    "interval": 10,
    "format": " {used:4.1f}/{total:4.1f}GiB", // (󰯍 {swapUsed:3.1f}/{swapTotal:3.1f}GiB)
    "tooltip": false
  },
  "network": {
    "interval": 5,
    "family": "ipv4",
    "format": "󰌘 {bandwidthDownBytes:>}  |{bandwidthUpBytes:>} ",
    "format-disconnected": "󰌙",
    "tooltip": true,
    "tooltip-format-wifi": "  WIFI\n󰩟 {ipaddr}/{cidr}@{ifname} via {gwaddr}\n {signalStrength}%",
    "tooltip-format-ethernet": "󰈀 WIRED\n󰩟 {ipaddr}/{cidr}@{ifname} via {gwaddr}",
    "tooltip-format": "{ifname} via {gwaddr}"
  },
  "battery": {
    "internal": 60,
    "bat": "BAT0",
    "states": {
      "good": 95,
      "warning": 30,
      "critical": 5
    },
    "format": "{icon} {capacity:3}%",
    "format-icons": [
      "",
      "",
      "",
      "",
      ""
    ],
    "format-charging": "󰂅 {capacity:3}%",
    "format-plugged": " {capacity:3}%"
  },
  "wireplumber": {
    "node-type": "Audio/Sink",
    "format": "{icon} {volume:3}%",
    "format-icons": [
      "",
      "",
      ""
    ],
    "format-muted": "󰝟 HUSH",
    "on-click": "wpctl set-mute @DEFAULT_AUDIO_SINK@ toggle",
    "scroll-step": 5,
    "max-volume": 100
  },
  "wireplumber#source": {
    "node-type": "Audio/Source",
    "format": "󰍬 {volume:3}%",
    "format-muted": "󰍭 MUTE",
    "on-click": "wpctl set-mute @DEFAULT_AUDIO_SOURCE@ toggle",
    "scroll-step": 5
  },
  "clock": {
    "locale": "de_DE.UTF-8",
    "calendar": {
      "mode": "month",
      "weeks-pos": "left",
      "format": {
        "today": "<span color='#EA6962'>{}</span>"
      }
    },
    "format": "󱑂 {:%H:%M}", // %d.%m
    "tooltip-format": "<tt>{calendar}</tt>"
  }
}

Expected behaviour
Waybar starts correctly on first launch.

Screenshots
n/a

Environment

• Waybar version (waybar --version): Waybar v0.15.0 (branch 'HEAD')
• Installed from (distro package / source / other): built from source on Ubuntu 26.04
• Compositor and version (Sway, Hyprland, River, …): swayfx version 0.5.3-1ccec2a (May 10 2026, branch 'master') (based on sway 1.11.0)

Debug output
I used journalctl --user -b -u waybar.service to get the log of the current boot:

Jul 06 21:28:52 midgard systemd[3616]: Started waybar.service - Waybar | Highly Customizable Wayland Bar.
Jul 06 21:28:54 midgard waybar[3966]: [2026-07-06 21:28:54.598] [error] [wireplumber]: Object '35' not found
Jul 06 21:28:54 midgard waybar[3966]: [2026-07-06 21:28:54.599] [error] Object '35' not found
Jul 06 21:29:03 midgard waybar[3966]: /usr/include/c++/15/bits/regex_executor.tcc:544: void std::__detail::_Executor< <template-parameter-1-1>, <template-parameter-1-2>, <template-parameter-1-3>, <anonymous> >::_M_dfs(_Match_mode, std::__detail::_StateIdT) [with _BiIter = __gnu_cxx::__normal_iterator<const cha>
Jul 06 21:29:03 midgard waybar[3966]: /usr/include/c++/15/bits/regex_executor.tcc:544: void std::__detail::_Executor< <template-parameter-1-1>, <template-parameter-1-2>, <template-parameter-1-3>, <anonymous> >::_M_dfs(_Match_mode, std::__detail::_StateIdT) [with _BiIter = __gnu_cxx::__normal_iterator<const cha>
Jul 06 21:29:05 midgard systemd[3616]: waybar.service: Main process exited, code=dumped, status=6/ABRT
Jul 06 21:29:05 midgard systemd[3616]: waybar.service: Failed with result 'core-dump'.
Jul 06 21:29:06 midgard systemd[3616]: waybar.service: Scheduled restart job, restart counter is at 1.
Jul 06 21:29:06 midgard systemd[3616]: Started waybar.service - Waybar | Highly Customizable Wayland Bar.

Additional context
I am not sure whether and how the issue is related to Wireplumber. It seems to go away, though, when the audio modules are disabled.