Check two visible signals before changing anything: whether YouTube has captions for the video, and whether Language Reactor itself is present on the page.
If Language Reactor disappears on one YouTube video, don’t immediately perform the sacred uninstall-reinstall ceremony. Look for two lights first: does YouTube show CC, and does Language Reactor itself appear? Those two answers tell you whether to investigate the source video or the extension ErweiterungGerman: extension; a browser tool that adds practice controls layer.
Start with the two-light dashboard: CC and LR
No YouTube CC/captions are available on this video
Stay on the YouTube side first. A missing caption track is useful evidence about the source video. It does not prove Language Reactor is broken, and it does not mean you should reinstall the extension. Check another clearly captioned video before changing the browser.
YouTube captions work, but the Language Reactor button or overlay is missing
Move to the Language Reactor layer. Its current FAQ directs missing-extension-UI cases toward the correct current extension, blockers and required permissions. This is the branch where extension troubleshooting belongs.
YouTube captions and Language Reactor both appear, but one LR feature fails
Name the feature that actually fails. “Language Reactor is not working” is now too broad. Is word lookup missing? Is a subtitle subtítulosSpanish: subtitles; the text line under the scene control behaving unexpectedly? Is a saved-item action the problem? A partial failure deserves a narrower diagnosis than a missing extension.
Language Reactor works on other YouTube videos but not this one
Compare the caption state first, then repeat the exact same LR action on another clearly captioned video. A one-video symptom is useful evidence, but it does not by itself prove a YouTube bug, a Language Reactor bug, or an outage.
Layer 1: does YouTube itself have captions?
YouTube’s current desktop subtitle help says the Closed Captions control appears when captions are available. Captions may have been added by the video owner or generated automatically by YouTube.
So before you inspect extension permissions, look at the YouTube player:
- Is the CC control visible?
- Can you turn captions on in YouTube itself?
- Does the caption menu contain the language or track you expected?
If native YouTube captions are not currently available, do not jump from “no caption track” to “the extension is broken.” For subtitle-related expectations, the source layer is already different from a video where YouTube exposes captions.
That also does not justify the opposite overclaim: this article is not saying every Language Reactor feature absolutely requires a YouTube caption track. The point is simpler. Caption availability is one independent part of the setup, and you should inspect it before diagnosing the extension.
Why automatic captions may be missing or delayed
No CC on one video does not necessarily mean “this video will never have captions.” YouTube’s current automatic-captioning help lists several reasons auto-captions may not be available yet or may not be generated.
The video is new and captions may still be processing
YouTube notes that automatic captions can take time to become available. If the upload is recent, changing Language Reactor settings does nothing to speed up YouTube’s caption-processing state.
The language or audio TonspurGerman: audio track; the spoken track you train with is difficult for automatic captioning
YouTube documents unsupported languages and poor sound quality or difficult speech recognition among the reasons automatic captions may not be available.
The video has long silence, overlapping speakers or multiple languages
YouTube also documents long silence at the beginning, overlapping speakers and multiple languages as situations that can prevent automatic captions from being produced reliably.
The video is unusually long
YouTube includes video length among the documented reasons automatic captioning may not be available.
These are possible YouTube-side conditions, not a diagnosis of the exact video in front of you. The useful action is to observe whether captions are actually available, not to guess which hidden reason applies.
Layer 2: is Language Reactor actually present?
If YouTube captions are available but Language Reactor’s button, overlay or expected interface is absent, now you have a different symptom.
Language Reactor’s current Get Started guide documents YouTube as one of the places where its browser extension adds language-learning controls. Its current FAQ says that when the extension button is missing on Netflix or YouTube, users should check that they have the correct current extension, consider whether a domain blocker is interfering, and make sure the extension has the required permissions.
That is much more useful than blindly clearing browser data because the FAQ is pointing at the layer that is visibly missing.
Check the extension state before you reinstall it
Only after the simpler state checks fail does reinstalling become a reasonable next experiment. Reinstalling first is a lower-information move: it changes the setup before you have learned whether the original problem was captions, permissions or one specific video.
If both lights are on, stop saying “Language Reactor doesn’t work”
This is the underrated branch. YouTube captions exist. Language Reactor is visibly loaded. Something still feels wrong.
Now describe the exact failure:
- “The LR overlay is present, but clicking this subtitle word does nothing.”
- “The controls appear, but the behavior differs on this one video.”
- “The extension loads, but the caption-related feature I expected is not available on this title.”
Those are useful symptoms. “It’s broken” is not. The smaller your description becomes, the less likely you are to perform browser archaeology on a feature-level problem.
Run the same-setup, different-video check
If one YouTube video is the troublemaker, use another clearly captioned video as a comparison. You are not trying to prove a universal bug; you are asking whether the symptom follows the setup.
If the same LR function works on the comparison video, the original video has become an important part of the reproduction. If it fails on both, the case for a broader extension/setup issue becomes stronger. Neither result identifies the precise hidden cause by itself—and that restraint is a feature, not a weakness.
If it is still broken, build a useful report instead of a mystery
At this point you can describe the problem in a way that someone can actually investigate:
- whether YouTube CC/captions are available on the affected video;
- whether Language Reactor’s button/overlay appears;
- the exact LR function that fails;
- whether the extension is enabled and has its expected permissions;
- whether the same function works on another clearly captioned YouTube video.
That is a radically better starting point than “Language Reactor stopped working on YouTube.” You have separated the source layer from the extension layer without inventing a cause.
If your bigger goal is simply studying inside supported videos
Once you have finished the diagnosis, you may decide you care less about repairing one exact tool and more about having a workable video-learning setup. FunFluen offers another supported-video learning workflow where the required video and subtitle context is available.
It is not a fix for a missing YouTube caption track, and it does not repair Language Reactor or guarantee support for every video.
Explore another supported-video learning workflow by opening FunFluen’s product home and seeing whether the current setup fits how you study.
For the broader method behind subtitles, replay 반복Korean: repetition; play it again until it sticks and active practice, see the media-based language learning setup.
Check the layer before the repair
Keep the two-light dashboard in your head: CC tells you about the YouTube source layer; LR tells you about the Language Reactor layer.
No captions? Investigate the source-video state first. Captions available but Language Reactor missing? Check the extension, blockers and permissions. Both present but one feature fails? Name that feature and compare another captioned video.
That sequence is less dramatic than reinstalling everything. It is also much better at telling you what is actually worth fixing.