ErrorBase
Independent technical referenceOfficial site
  • Software and digital services
  • Web browsers

ERR_HTTP2_PROTOCOL_ERROR

ERR_HTTP2_PROTOCOL_ERROR in Google Chrome: HTTP/2 protocol error

Verified with sources3 sourcesReviewed Oct 3, 2026
Technician coming? See the 2 steps they must show you

Risk level

Low

Usually safe to check without specialist tools.

Urgency

Medium

Quick answer

Chrome detected an error in the HTTP/2 exchange with the site. Reload, try Incognito without extensions and check your antivirus; if it fails on all your devices, tell the site operator.

Safety first

Stop and check this first

  • If you turn the antivirus off to test, turn it back on when the test is over.

Safe checks you can perform

  • Reload and other pages on the site
  • Incognito mode and extensions
  • Another device and security software
  • The server's HTTP/2 responses

Leave these tasks to a qualified professional

  • Do not attempt this professional task: Locate the invalid response
  • Do not attempt this professional task: Review connection inspection

What a technician must be able to justify

Technician visit

These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.

These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.

  1. Locate the invalid response

    What they doThe operator reviews server and delivery network logs for the address and time of the report.

    They must show youthe log that identifies the problematic response or header.

    In writingthe fix applied.

  2. Review connection inspection

    What they doThe administrator checks whether the antivirus or a network proxy inspects the device's HTTP/2 connections.

    They must show youthe setting involved.

    In writingthe change or exception.

Before accepting a part or repair

Nothing has been shown yet. Do not accept a part swap based on the code alone.

Follow these steps

Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.

  1. Reload and other pages on the site

    No special tools

    Who:
    you.
    How:
    reload and open other pages on the same site.
    Result that matters:
    whether one page fails or the whole site.
    If only one page fails:
    it indicates something in that page's response; note the address.
    If the whole site fails:
    continue with Incognito and another device.
    Evidence to keep:
    failing addresses and time.

    Evidence: Google Chrome Help - Fix connection and loading errors in Chrome

  2. Incognito mode and extensions

    No special tools

    Who:
    you.
    How:
    open the page in Incognito; if it works, disable extensions and turn them on one at a time.
    Result that matters:
    whether an extension triggers the error.
    If an extension triggers it:
    it is the cause; keep it off for that site.
    If it also fails in Incognito:
    rule out extensions.
    Evidence to keep:
    extension name, if any.

    Evidence: Google Chrome Help - Fix connection and loading errors in Chrome

  3. Another device and security software

    No special tools

    Who:
    you.
    How:
    open the page on another device; if it works there, check whether your antivirus or firewall inspects web connections.
    Result that matters:
    whether the error depends on this device.
    If it only fails on this device:
    it points to its security software.
    If it fails on every device:
    it points to the site; tell the operator the address and the time.
    Evidence to keep:
    list of devices tried.

    On a work computer, do not touch the antivirus: ask the administrator to run the test.

    Evidence: Google Chrome Help - Fix connection and loading errors in Chrome

  4. The server's HTTP/2 responses

    Tools required

    Who:
    the site operator.
    How:
    review server and delivery network logs for that address and time, and compare the response over HTTP/2 and over HTTP/1.1.
    Result that matters:
    which component produces the invalid response.
    If it only fails over HTTP/2 at the server:
    the cause is in its HTTP/2 implementation or configuration.
    If it only fails through an intermediary:
    it indicates that intermediary alters the response.
    Evidence to keep:
    logs with the time and the compared response.

    Only the site operator. If you do not run it, do not tamper with anything.

    Evidence: RFC 9113 - HTTP/2

Still not solved

If the error persists, stop here. See what the technician must do and show you.

Where this code applies

A code is meaningful only inside the right product and version context.

Primary scope

System
Software and digital services
Brand
Google Chrome
Product type
Web browsers

Known code variants

  • ERR_HTTP2_PROTOCOL_ERROR
  • ERR_HTTP2_PROTOCOL_ERROR (-337)
  • ERR_HTTP2_PROTOCOL_ERROR Chrome
  • net::ERR_HTTP2_PROTOCOL_ERROR

What it means

Chromium defines ERR_HTTP2_PROTOCOL_ERROR (-337) as an HTTP/2 protocol error, within its HTTP error range. HTTP/2 is defined in RFC 9113, whose PROTOCOL_ERROR code is used for unspecific protocol errors. Chrome's code does not say which message was wrong or who sent it: it can be the server, an intermediary such as a delivery network, or software inspecting the connection on your device.

Warnings and stop conditions

  • Loweditorial warning

    If you turn the antivirus off to test, turn it back on when the test is over.

    Evidence: Google Chrome Help - Get help with common error messages in Chrome

Symptoms and causes

Probable causes · in order

  • Invalid HTTP/2 response from the server or an intermediaryPossible

    The failure repeats from several devices and networks on the same page.

    Evidence: Chromium source - net/base/net_error_list.h (network error list) · RFC 9113 - HTTP/2

  • Extension, antivirus or firewall stepping inPossible

    The failure disappears in Incognito or on another device on the same network.

    Evidence: Google Chrome Help - Fix connection and loading errors in Chrome

Virtual technician

Does ERR_HTTP2_PROTOCOL_ERROR still appear after these checks?

Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.

Start diagnosis

Sources and technical references

  1. 1

    Chromium source - net/base/net_error_list.h (network error list)

    The Chromium Authors · 2026 · official_doc

  2. 2

    Google Chrome Help - Fix connection and loading errors in Chrome

    Google · 2026 · official_doc

  3. 3

    RFC 9113 - HTTP/2

    IETF / RFC Editor · 2022 · standard

Sources: Chromium source - net/base/net_error_list.h (network error list) · Google Chrome Help - Fix connection and loading errors in Chrome · RFC 9113 - HTTP/2reviewed 2026-10-03 · verified

Was this entry useful?