# Development

**URL:** https://discourse.mozilla.org/c/add-ons/development/108.md

[Latest](https://discourse.mozilla.org/latest.md) · [Categories](https://discourse.mozilla.org/categories.md) · [Tags](https://discourse.mozilla.org/tags.md)

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## [Get started with Firefox extension development](https://discourse.mozilla.org/t/get-started-with-firefox-extension-development/76051)

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**Author:** [@caitlin](https://discourse.mozilla.org/u/caitlin)\
**Replies:** 5\
**Last updated:** [September 30, 2025, 9:55pm UTC](https://discourse.mozilla.org/t/get-started-with-firefox-extension-development/76051 "2025-09-30T21:55:13Z")

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Extensions provide a simple and powerful way to personalize your browsing experience. If you know JavaScript, CSS, and HTML, you can build your own. If you are brand-new to add-on development, you can get started by che…

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## [About the Development category](https://discourse.mozilla.org/t/about-the-development-category/2162)

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**Author:** [@yousef](https://discourse.mozilla.org/u/yousef)\
**Replies:** 0\
**Last updated:** [May 21, 2015, 10:28am UTC](https://discourse.mozilla.org/t/about-the-development-category/2162 "2015-05-21T10:28:13Z")

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Technical discussions about add-on development. You can email addons+development@mozilla-community.org to post to this category.

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## [Corrupted sessionstore.jsonlz4 file?](https://discourse.mozilla.org/t/corrupted-sessionstore-jsonlz4-file/149555)

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**Author:** [@hapztuh1567](https://discourse.mozilla.org/u/hapztuh1567)\
**Replies:** 1\
**Last updated:** [September 25, 2026, 7:24pm UTC](https://discourse.mozilla.org/t/corrupted-sessionstore-jsonlz4-file/149555 "2026-09-25T19:24:29Z")

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I’ve been dealing with this for a long time. Usually, after the profile has been in use for a while, this profile may either slow down, or freeze/crash and incapacitate my system. Definitely related to maxing out memor…

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## [How to create a discarded tab with favicon loaded?](https://discourse.mozilla.org/t/how-to-create-a-discarded-tab-with-favicon-loaded/149422)

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**Author:** [@lionelw](https://discourse.mozilla.org/u/lionelw)\
**Replies:** 4\
**Last updated:** [September 19, 2026, 3:05pm UTC](https://discourse.mozilla.org/t/how-to-create-a-discarded-tab-with-favicon-loaded/149422 "2026-09-19T15:05:57Z")

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Creating a tab via await browser.tabs.create({ url: 'https://www.example.com/', discarded: true }); yields a discarded tab that’s missing its title (not an issue) and its favicon (my issue). I’ve thought of one way to…

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## [Unable to generate API key](https://discourse.mozilla.org/t/unable-to-generate-api-key/149412)

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**Author:** [@miles\_abbott](https://discourse.mozilla.org/u/miles_abbott)\
**Replies:** 3\
**Last updated:** [September 11, 2026, 3:23pm UTC](https://discourse.mozilla.org/t/unable-to-generate-api-key/149412 "2026-09-11T15:23:29Z")

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I am attempting to generate an API key. However, the Manage API Keys page repeatedly displays the message You have submitted this form too many times recently. Please try again later. This issue arose after I updated my …

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## [How to detect / identify PWA (web apps) windows?](https://discourse.mozilla.org/t/how-to-detect-identify-pwa-web-apps-windows/149166)

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**Author:** [@juraj.masiar](https://discourse.mozilla.org/u/juraj.masiar)\
**Replies:** 1\
**Last updated:** [September 7, 2026, 12:18pm UTC](https://discourse.mozilla.org/t/how-to-detect-identify-pwa-web-apps-windows/149166 "2026-09-07T12:18:59Z")

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Firefox has now web-apps support: But I’m unable to “detect” web-app being opened. For example: browser.windows.onCreated.addListener(console.log); // will print this after opening "WhatsApp" from taskbar: { "id": …

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## [Add-on API key request email rate limit](https://discourse.mozilla.org/t/add-on-api-key-request-email-rate-limit/149269)

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**Author:** [@RougeEric](https://discourse.mozilla.org/u/RougeEric)\
**Replies:** 1\
**Last updated:** [August 26, 2026, 3:04pm UTC](https://discourse.mozilla.org/t/add-on-api-key-request-email-rate-limit/149269 "2026-08-26T15:04:46Z")

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Context I am trying to get a Mozilla Developer Hub API Key to start publishing an add-on. Issue I visited https://addons.mozilla.org/en-US/developers/addon/api/key/ and requested an email. As the emails didn’t seem to c…

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## [Is it possible to modify the context menu display name for a dictionary?](https://discourse.mozilla.org/t/is-it-possible-to-modify-the-context-menu-display-name-for-a-dictionary/148990)

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**Author:** [@dcooper\_mozillaid](https://discourse.mozilla.org/u/dcooper_mozillaid)\
**Replies:** 0\
**Last updated:** [July 19, 2026, 8:02pm UTC](https://discourse.mozilla.org/t/is-it-possible-to-modify-the-context-menu-display-name-for-a-dictionary/148990 "2026-07-19T20:02:34Z")

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I have been trying to develop a custom Firefox dictionary add-on that bundles multiple distinct botanical word lists into a single extension using Manifest V3. My manifest.json defines the dictionaries like this: “dict…

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## [Why malicious extensions get deleted "silently" ? how about transparent "Tombstone" pages instead](https://discourse.mozilla.org/t/why-malicious-extensions-get-deleted-silently-how-about-transparent-tombstone-pages-instead/148959)

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**Author:** [@David\_R](https://discourse.mozilla.org/u/David_R)\
**Replies:** 2\
**Last updated:** [July 17, 2026, 10:04am UTC](https://discourse.mozilla.org/t/why-malicious-extensions-get-deleted-silently-how-about-transparent-tombstone-pages-instead/148959 "2026-07-17T10:04:11Z")

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Hey everyone, When Firefox or Chrome removes a malicious extension, it usually vanishes into thin air. It gets disabled in browser, and the store link turns into a generic “Oops! We can’t find that page”. While pulling…

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## [\_paranioa\_allocator\_ virus mozilla subprocess insecure. offering solutions](https://discourse.mozilla.org/t/paranioa-allocator-virus-mozilla-subprocess-insecure-offering-solutions/148955)

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**Author:** [@ziongamerrush\_accessdenied](https://discourse.mozilla.org/u/ziongamerrush_accessdenied)\
**Replies:** 0\
**Last updated:** [July 16, 2026, 7:27am UTC](https://discourse.mozilla.org/t/paranioa-allocator-virus-mozilla-subprocess-insecure-offering-solutions/148955 "2026-07-16T07:27:03Z")

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several functions apeer when opening a new tab causing google authorization process to take far longer then normal to open the webpage, before these fake sub processes apeered in the shift+escape process manager tab g…

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## [Does a "Reading manifest" warning prevent install/update for regular users? (data\_collection\_permissions for ESR 115)](https://discourse.mozilla.org/t/does-a-reading-manifest-warning-prevent-install-update-for-regular-users-data-collection-permissions-for-esr-115/148911)

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**Author:** [@duncan.lang](https://discourse.mozilla.org/u/duncan.lang)\
**Replies:** 4\
**Last updated:** [July 14, 2026, 4:43pm UTC](https://discourse.mozilla.org/t/does-a-reading-manifest-warning-prevent-install-update-for-regular-users-data-collection-permissions-for-esr-115/148911 "2026-07-14T16:43:29Z")

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I’ve been holding off to add data\_collection\_permissions to by add-on manifest as the property has a minimum browser version is 140, even though Firefox still supports 115 ESR. I just installed the 115 ESR to see how it …

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## [AMO won't let me re-upload version 2.9.3 after I deleted my previous 2.9.3 upload, and I can't delete the whole extension to start over](https://discourse.mozilla.org/t/amo-wont-let-me-re-upload-version-2-9-3-after-i-deleted-my-previous-2-9-3-upload-and-i-cant-delete-the-whole-extension-to-start-over/148921)

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**Author:** [@Charlieee1](https://discourse.mozilla.org/u/Charlieee1)\
**Replies:** 1\
**Last updated:** [July 13, 2026, 6:39am UTC](https://discourse.mozilla.org/t/amo-wont-let-me-re-upload-version-2-9-3-after-i-deleted-my-previous-2-9-3-upload-and-i-cant-delete-the-whole-extension-to-start-over/148921 "2026-07-13T06:39:02Z")

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I’m developing a Firefox extension with add-on ID {243e7bef-...}. My workflow so far: I uploaded version 2.9.3 as my first submission. That release ended up unusable, so I deleted that version. I then tried to re-uploa…

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## [Mozilla Review Delays Preventing My Self-Distributed Extension Registration](https://discourse.mozilla.org/t/mozilla-review-delays-preventing-my-self-distributed-extension-registration/148554)

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**Author:** [@masatoshi.hayashi](https://discourse.mozilla.org/u/masatoshi.hayashi)\
**Replies:** 2\
**Last updated:** [July 1, 2026, 4:59am UTC](https://discourse.mozilla.org/t/mozilla-review-delays-preventing-my-self-distributed-extension-registration/148554 "2026-07-01T04:59:35Z")

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On May 16, I submitted the following extension to Firefox AMO for signing. Extensions id: markii\_recorder\_browser\_extension@infotrace.mk2 Compared to the previous version, this update only modifies the update\_url valu…

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## [\[Feedback\] VoxSub – a Firefox add-on for dual subtitles, AI translation, and subtitle control](https://discourse.mozilla.org/t/feedback-voxsub-a-firefox-add-on-for-dual-subtitles-ai-translation-and-subtitle-control/148583)

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**Author:** [@VoxSubDev](https://discourse.mozilla.org/u/VoxSubDev)\
**Replies:** 8\
**Last updated:** [June 25, 2026, 8:00pm UTC](https://discourse.mozilla.org/t/feedback-voxsub-a-firefox-add-on-for-dual-subtitles-ai-translation-and-subtitle-control/148583 "2026-06-25T20:00:34Z")

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Hi everyone, I’m building a Firefox add-on called VoxSub. The main problem I’m trying to solve is that many online video players only provide one subtitle track, or the available subtitle is not in the language or style…

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## [Requesting \`file:///\*\` permission dynamically via \`browser.permissions.request()\`](https://discourse.mozilla.org/t/requesting-file-permission-dynamically-via-browser-permissions-request/148722)

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**Author:** [@ariel.risky](https://discourse.mozilla.org/u/ariel.risky)\
**Replies:** 1\
**Last updated:** [June 24, 2026, 6:59pm UTC](https://discourse.mozilla.org/t/requesting-file-permission-dynamically-via-browser-permissions-request/148722 "2026-06-24T18:59:27Z")

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Hey all, With Firefox 153 making file access opt-in (here), I’ve been thinking about how extensions should handle this. Currently, browser.permissions.request() works fine for requesting host permissions like "\<all\_url…

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## [You should make a "How to make an extension" video for vibe coders](https://discourse.mozilla.org/t/you-should-make-a-how-to-make-an-extension-video-for-vibe-coders/148693)

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**Author:** [@Ano\_Ano](https://discourse.mozilla.org/u/Ano_Ano)\
**Replies:** 3\
**Last updated:** [June 22, 2026, 12:22pm UTC](https://discourse.mozilla.org/t/you-should-make-a-how-to-make-an-extension-video-for-vibe-coders/148693 "2026-06-22T12:22:23Z")

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I am a new vibe coder and know how to make most things but not extensions. If you want people to make more firefox extensions you should really make a video. There is not a single one showing how to do right now

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## [Locked Dashboard: Clarification on False Positive (UUID: b0dd6398-1c58-4940-b0be-3577cd03b723)](https://discourse.mozilla.org/t/locked-dashboard-clarification-on-false-positive-uuid-b0dd6398-1c58-4940-b0be-3577cd03b723/148619)

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**Author:** [@Muhammad\_Talha](https://discourse.mozilla.org/u/Muhammad_Talha)\
**Replies:** 2\
**Last updated:** [June 15, 2026, 9:20am UTC](https://discourse.mozilla.org/t/locked-dashboard-clarification-on-false-positive-uuid-b0dd6398-1c58-4940-b0be-3577cd03b723/148619 "2026-06-15T09:20:36Z")

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Hello AMO Staff, My extension, Qalam 2.0, was recently disabled by the automated scanner under the “Deceptive or misleading” policy (UUID: b0dd6398-1c58-4940-b0be-3577cd03b723). I am posting here because my developer h…

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## [YouTube embed in extension no longer possible?](https://discourse.mozilla.org/t/youtube-embed-in-extension-no-longer-possible/148624)

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**Author:** [@freaktechnik](https://discourse.mozilla.org/u/freaktechnik)\
**Replies:** 0\
**Last updated:** [June 11, 2026, 10:25pm UTC](https://discourse.mozilla.org/t/youtube-embed-in-extension-no-longer-possible/148624 "2026-06-11T22:25:52Z")

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I have an extension (mostly for my own amusement) that embeds a youtube-nocookie embed in an extension page. This has worked fine until recently, where recently is somewhere in the past ~7 months. From what I understand …

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## [Cannot load extensions with background scripts](https://discourse.mozilla.org/t/cannot-load-extensions-with-background-scripts/66342)

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**Author:** [@bijex](https://discourse.mozilla.org/u/bijex)\
**Replies:** 5\
**Last updated:** [June 8, 2026, 12:45pm UTC](https://discourse.mozilla.org/t/cannot-load-extensions-with-background-scripts/66342 "2026-06-08T12:45:28Z")

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I am trying to make an extension for my personal use. I started writing a couple lines of code and it works in google chrome, but the same extension gives me an error on firefox. The extension needs only a background sc…

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## [\[Showcase\] Building a Global Media Controller for Firefox (Proof-of-Concept)](https://discourse.mozilla.org/t/showcase-building-a-global-media-controller-for-firefox-proof-of-concept/148406)

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**Author:** [@MK2010GAMER](https://discourse.mozilla.org/u/MK2010GAMER)\
**Replies:** 2\
**Last updated:** [May 23, 2026, 2:51am UTC](https://discourse.mozilla.org/t/showcase-building-a-global-media-controller-for-firefox-proof-of-concept/148406 "2026-05-23T02:51:09Z")

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I’ve developed a lightweight extension to add a feature that Firefox currently completely lacks: a native, global media controller. The Problem: Firefox has no centralized, global UI for users to view or control media p…

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## [Extensions panel uses wrong themed icon colour](https://discourse.mozilla.org/t/extensions-panel-uses-wrong-themed-icon-colour/148382)

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**Author:** [@keunes](https://discourse.mozilla.org/u/keunes)\
**Replies:** 0\
**Last updated:** [May 19, 2026, 8:30am UTC](https://discourse.mozilla.org/t/extensions-panel-uses-wrong-themed-icon-colour/148382 "2026-05-19T08:30:54Z")

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Hello, I’m making an extension (well, getting AI to do so) and I’m having difficulties getting the icon colour right. Goal: making the icon visible both in light and dark mode. I have specified icons as such in manifes…

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## [Problem with internationalisation management](https://discourse.mozilla.org/t/problem-with-internationalisation-management/148219)

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**Author:** [@wronschien](https://discourse.mozilla.org/u/wronschien)\
**Replies:** 10\
**Last updated:** [May 6, 2026, 8:55am UTC](https://discourse.mozilla.org/t/problem-with-internationalisation-management/148219 "2026-05-06T08:55:10Z")

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This is a copy of a post I made on reddit r/FirefoxAddons/, I’ve been advised to also post here so here we go. Being fairly new to development, I made a test addon with a background script containing a non-ascii charact…

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## [Appeal: RavenWallet removal was triggered by coordinated fake review attack](https://discourse.mozilla.org/t/appeal-ravenwallet-removal-was-triggered-by-coordinated-fake-review-attack/148024)

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**Author:** [@Darko\_Simonovski](https://discourse.mozilla.org/u/Darko_Simonovski)\
**Replies:** 8\
**Last updated:** [April 29, 2026, 3:00pm UTC](https://discourse.mozilla.org/t/appeal-ravenwallet-removal-was-triggered-by-coordinated-fake-review-attack/148024 "2026-04-29T15:00:29Z")

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Hi, My extension RavenWallet was removed for “deceptive, misleading, or fraudulent activity.” This is incorrect - the removal was triggered by a coordinated bot attack that posted ~100 fake 1-star reviews within a 10-mi…

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## [Add-On code help](https://discourse.mozilla.org/t/add-on-code-help/148100)

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**Author:** [@Tyler\_Ing](https://discourse.mozilla.org/u/Tyler_Ing)\
**Replies:** 1\
**Last updated:** [April 25, 2026, 6:05pm UTC](https://discourse.mozilla.org/t/add-on-code-help/148100 "2026-04-25T18:05:10Z")

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I am trying to make an Add-on to help simplify daily things I do at work. I have already made the addon and it works fine, but I’m trying to improve it but I’ve run into issues. The addon’s popup window scrapes data from…

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## [Strongly recommend adding hook native JavaScript function functionality](https://discourse.mozilla.org/t/strongly-recommend-adding-hook-native-javascript-function-functionality/148050)

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**Author:** [@yigeyonghu](https://discourse.mozilla.org/u/yigeyonghu)\
**Replies:** 1\
**Last updated:** [April 23, 2026, 9:38pm UTC](https://discourse.mozilla.org/t/strongly-recommend-adding-hook-native-javascript-function-functionality/148050 "2026-04-23T21:38:01Z")

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The current WebExtensions JavaScript API is very weak. Many useful functional ideas cannot be realized. For example, if I want to implement a clipboard management extension that statistically intercepts junk clipboard c…

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## [Add-On Removed and account Banned](https://discourse.mozilla.org/t/add-on-removed-and-account-banned/147977)

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**Author:** [@sandboxlabo](https://discourse.mozilla.org/u/sandboxlabo)\
**Replies:** 1\
**Last updated:** [April 21, 2026, 11:17pm UTC](https://discourse.mozilla.org/t/add-on-removed-and-account-banned/147977 "2026-04-21T23:17:02Z")

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Hi Mozilla Team, I am writing to appeal the sudden ban of my developer account and the removal of my extension. My extension (ID: 2936283, version 1.1) was previously approved and has been functioning without issues si…

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## [How to attach cookie to request?](https://discourse.mozilla.org/t/how-to-attach-cookie-to-request/148059)

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**Author:** [@vietan0](https://discourse.mozilla.org/u/vietan0)\
**Replies:** 2\
**Last updated:** [April 21, 2026, 1:58pm UTC](https://discourse.mozilla.org/t/how-to-attach-cookie-to-request/148059 "2026-04-21T13:58:03Z")

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I want to send a request from the content script to an external site, which requires a cookie to authenticate. I’m already logged in so I got the cookie, but couldn’t attach it to the fetch. await fetch(url, { headers…

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## [UnknownError: The operation failed for reasons unrelated to the database itself and not covered by any other error code](https://discourse.mozilla.org/t/unknownerror-the-operation-failed-for-reasons-unrelated-to-the-database-itself-and-not-covered-by-any-other-error-code/148044)

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**Author:** [@juraj.masiar](https://discourse.mozilla.org/u/juraj.masiar)\
**Replies:** 0\
**Last updated:** [April 19, 2026, 2:29pm UTC](https://discourse.mozilla.org/t/unknownerror-the-operation-failed-for-reasons-unrelated-to-the-database-itself-and-not-covered-by-any-other-error-code/148044 "2026-04-19T14:29:45Z")

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Anyone else is seeing higher than usual amount of reports from Firefox 149 users regarding broken IndexedDB database?

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## [Testing an add-on on restart](https://discourse.mozilla.org/t/testing-an-add-on-on-restart/147920)

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**Author:** [@plwt](https://discourse.mozilla.org/u/plwt)\
**Replies:** 2\
**Last updated:** [April 12, 2026, 7:36pm UTC](https://discourse.mozilla.org/t/testing-an-add-on-on-restart/147920 "2026-04-12T19:36:43Z")

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Hi. I am working on an add-on that performs an action when Fx updates. How could I test this? If I install the .xpi using about:debugging, the add-on is removed on restart. Is there a better way that might work?

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## [Why I can't see the content script when I debug the addon?](https://discourse.mozilla.org/t/why-i-cant-see-the-content-script-when-i-debug-the-addon/51635)

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**Author:** [@805888196](https://discourse.mozilla.org/u/805888196)\
**Replies:** 12\
**Last updated:** [April 11, 2026, 11:43pm UTC](https://discourse.mozilla.org/t/why-i-cant-see-the-content-script-when-i-debug-the-addon/51635 "2026-04-11T23:43:00Z")

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[Next page](https://discourse.mozilla.org/c/add-ons/development/108.md?page=1)