# Modifying sorce code of installed add-ons

**URL:** <https://discourse.mozilla.org/t/modifying-sorce-code-of-installed-add-ons/24408>\
**Category:** Development\
**Created:** [January 14, 2018, 10:51pm UTC](https://discourse.mozilla.org/t/modifying-sorce-code-of-installed-add-ons/24408 "2018-01-14T22:51:28Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![juraj.masiar](https://sea1.discourse-cdn.com/flex001/user_avatar/discourse.mozilla.org/juraj.masiar/32/30587_2.png) [@juraj.masiar](https://discourse.mozilla.org/u/juraj.masiar)\
**Post date:** [January 14, 2018, 10:51pm UTC](https://discourse.mozilla.org/t/modifying-sorce-code-of-installed-add-ons/24408/1 "2018-01-14T22:51:28Z")

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Hello,

One of the users of my add-on GroupSpeedDial has a problem that I was not able to reproduce so I asked him to send me console logs from background script and there I saw several lines like this one:

```
Firefox nedokáže vytvoriť pripojenie k serveru ws://127.0.0.1:1001/?cid=624950170. background.js:20:122

```

Translated to English - “_Firefox cannot create connection to server ws://127.0.0.1:1001/?cid=624950170. background.js:20:122_”.

**Now the interesting part is that my production file “background.js” has only one line (so there cannot be error on line 20) and there is no Web-Socket in my whole add-on at all.**

So the source code had to be modified. But is this even possible? And for what purpose?

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**Author:** ![erosman](https://sea1.discourse-cdn.com/flex001/user_avatar/discourse.mozilla.org/erosman/32/15447_2.png) [@erosman](https://discourse.mozilla.org/u/erosman)\
**Post date:** [January 15, 2018, 6:32am UTC](https://discourse.mozilla.org/t/modifying-sorce-code-of-installed-add-ons/24408/2 "2018-01-15T06:32:54Z")

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> [@juraj.masiar](#):
>
> So the source code had to be modified. But is this even possible?

No. It is often the case that the errors belong to another `background.js`

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<div class="post-metadata">

**Author:** ![juraj.masiar](https://sea1.discourse-cdn.com/flex001/user_avatar/discourse.mozilla.org/juraj.masiar/32/30587_2.png) [@juraj.masiar](https://discourse.mozilla.org/u/juraj.masiar)\
**Post date:** [January 15, 2018, 10:07am UTC](https://discourse.mozilla.org/t/modifying-sorce-code-of-installed-add-ons/24408/3 "2018-01-15T10:07:39Z")

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**Thank you.**  
You were right, I just received more information and indeed it belonged to another add-on (Internet Download Manager).