HARPA AI Not Working on YouTube? Causes and Fixes (2026)

Quick answer: HARPA is a page-aware extension with a lot of configuration, which means it has more failure points than a simple summarizer. The three that account for most YouTube problems are: the extension is not reading the page (injection or permissions), the configured model or API key is not working, and the video has no caption track. Work through them in that order — the third is free to check and rules out everything else.

Start here: does the video have a transcript?

Open the video, click the three-dot menu underneath, and look for Show transcript. If it is not there, no transcript-based tool will summarize this video and the extension is not at fault. Music-heavy uploads, very recent uploads, noisy recordings and less-supported languages frequently lack automatic captions. Details in "no transcript available" on YouTube.

The sidebar opens but never reads the page

If HARPA sits on "reading page" or returns an empty result, it is an injection problem rather than a model problem:

• Reload the video page properly. Navigating between videos inside YouTube does not always re-run page injection, because YouTube never actually reloads. A hard refresh on the video URL fixes a surprising share of cases.
• Check site permissions. The extension needs explicit access to youtube.com in your browser's extension settings.
• Disable other extensions. Ad blockers, privacy tools and rival AI sidebars compete to modify the same page. Turn everything else off, confirm HARPA works, then re-enable one at a time to find the culprit.
• Rule out a YouTube layout change. When YouTube ships interface updates, extensions that target specific page elements break until they are patched. If it stopped working for everyone at once, this is why — see summarizers breaking after an update.

Model and API key problems

HARPA can run against different models, including your own API key. That flexibility is genuinely useful and it introduces failure modes a single-purpose tool does not have: an expired or rate-limited key, a model that has been deprecated, an account with no remaining balance, or a configuration that was working and silently stopped. If summarization fails on every page rather than just YouTube, the problem is here rather than in page reading. Test with a plain article page to isolate it.

Quotas on the free tier

Free tiers meter actions, and summarization consumes more than a simple query. If it worked earlier today and does not now, check your remaining allowance before assuming a fault. This is a design characteristic rather than a bug, but it does mean the tool becomes unavailable precisely when you are using it heavily.

Long videos and partial summaries

A three-hour video produces a transcript of roughly 25,000–35,000 words. Depending on the model and how the page content is chunked, you may get a summary weighted heavily toward the opening. The symptom is a summary that is specific early and generic later, usually with no warning. If that matters to you, verify on a video whose ending you know before relying on it — background in summaries cut off on long videos.

When the configuration is the problem

HARPA rewards setup effort — if you want automations, custom commands and your own model, that flexibility is the point. But if what you actually want is a summary of a video, the configuration surface is overhead, and every element of it is something that can break at an inconvenient moment.

YT Summarizer has no configuration: paste a URL, get an overview, key points and takeaways in about a minute. Nothing to install, no API key, no page injection to fail when YouTube changes its markup, and no daily allowance to run out mid-session. Five free summaries, then one-time credit packs from $19 with credits that never expire.