Updates / Opera

Opera 139: Chromium 155 underneath, four new CSS and policy features

Stable Opera on the fleet is now 139.0.6053.22, on Chromium 155. margin-trim, symbols() and two more arrive; TLS and HTTP/2 unchanged.

Opera stable · 138.0.6044.24 → 139.0.6053.22 · 2026-10-31

Opera released 139 to stable on 2026-10-27, and new opera sessions on the fleet now run 139.0.6053.22 instead of 138.0.6044.24. Opera 139 moves its Chromium base from 154.0.8037.99 to 155.0.8059.85, so web platform changes follow Chromium 155. The fleet's build is a later 139 build than the 139.0.6053.15 in Opera's changelog, on the same Chromium 155.0.8059.85.

New

Chromium 155.0.8059.85 (Opera release notes, "Chromium is updated to 155.0.8059.85").
New CSS features that pages can feature-test: margin-trim, text-decoration-skip-spaces and the symbols() counter-style function (Chromium 155; ChromeStatus release notes).
A new permission policy, media-playback-while-not-visible, which our probe found on 139 and not on 138.
Opera's own changes: Web AI (local, browser-powered AI), "Make Opera Yours 2.0" on the Start Page, now enabled on all release streams, sidebar and tab fixes, H.264 playback fixes and crash fixes (Opera release notes).

Removed or changed

Nothing our probe checks was removed: no web API or Playwright feature that worked on 138 is missing on 139.

What sites see / detection

User agent and client hints: Chrome/155.0.0.0 … OPR/139.0.0.0 in the user agent, and the Sec-CH-UA brands change from Chromium 154, Opera 138, Not A(Brand 99 to Opera 139, Chromium 155, Not(A:Brand 24. The placeholder brand and the order change with each Chromium major.
TLS and HTTP/2 unchanged: the JA4 hash, the full TLS fingerprint hash, the cipher and extension counts, the HTTP/2 fingerprint and the header order are identical to 138. (JA3 differs between the two snapshots, as it does between any two Chromium connections: Chromium shuffles its TLS extension order.)
Bot checks unchanged: bot.sannysoft.com flagged one check (WebGL Renderer) before and after.

For scraping

Nothing to change in your code: launch options, the Playwright 1.60 client and wsUrl are the same, and every Playwright feature we test still works.
If you match user agents or client hints, expect Opera 139 to report Chromium 155, one major behind the fleet's stable Chrome (156).

Measured on the fleet

The same probe ran against 138.0.6044.24 and 139.0.6053.22 on the fleet, each when it went live: identity, TLS and HTTP/2 fingerprint, web platform features, Playwright features and bot checks. Host-dependent values (cores, memory, timings) are left out.

What the site sees: identity

	Before	After
User agent	Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/154.0.0.0 Safari/537.36 OPR/138.0.0.0	Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/155.0.0.0 Safari/537.36 OPR/139.0.0.0
Client hint brands	Chromium 154, Opera 138, Not A(Brand 99	Opera 139, Chromium 155, Not(A:Brand 24
Client hint full versions	Chromium 154.0.8037.99, Opera 138.0.6044.24, Not A(Brand 99.0.0.0	Opera 139.0.6053.22, Chromium 155.0.8059.85, Not(A:Brand 24.0.0.0

Web platform features added

CSS margin-trim (Chrome 155)
CSS text-decoration-skip-spaces (Chrome 155)
CSS symbols() (Chrome 155)
Permission policy media-playback-while-not-visible (Chrome 155)

Raw diff

{
  "engine": "opera",
  "label": "stable",
  "from": "138.0.6044.24",
  "to": "139.0.6053.22",
  "browser_version": {
    "before": "154.0.8037.99",
    "after": "155.0.8059.85"
  },
  "changes": {
    "identity": [
      {
        "field": "user_agent",
        "before": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/154.0.0.0 Safari/537.36 OPR/138.0.0.0",
        "after": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/155.0.0.0 Safari/537.36 OPR/139.0.0.0"
      },
      {
        "field": "client_hint_brands",
        "before": "Chromium 154, Opera 138, Not A(Brand 99",
        "after": "Opera 139, Chromium 155, Not(A:Brand 24"
      },
      {
        "field": "client_hint_full_versions",
        "before": "Chromium 154.0.8037.99, Opera 138.0.6044.24, Not A(Brand 99.0.0.0",
        "after": "Opera 139.0.6053.22, Chromium 155.0.8059.85, Not(A:Brand 24.0.0.0"
      }
    ],
    "network": [],
    "features": {
      "added": [
        {
          "key": "css_margin_trim",
          "label": "CSS `margin-trim` (Chrome 155)"
        },
        {
          "key": "css_text_decoration_skip_spaces",
          "label": "CSS `text-decoration-skip-spaces` (Chrome 155)"
        },
        {
          "key": "css_symbols",
          "label": "CSS `symbols()` (Chrome 155)"
        },
        {
          "key": "policy_media_playback_while_not_visible",
          "label": "Permission policy `media-playback-while-not-visible` (Chrome 155)"
        }
      ],
      "removed": []
    },
    "playwright": {
      "broke": [],
      "fixed": []
    },
    "fingerprint": [],
    "bot_checks": {
      "newly_failed": [],
      "newly_passed": [],
      "failed_before": 1,
      "failed_after": 1
    },
    "plain_http": [],
    "launch": {
      "before_ms": 1147,
      "after_ms": 512
    }
  },
  "host_dependent_ignored": [
    "hardware_concurrency",
    "device_memory",
    "launch/connect/page timings"
  ]
}