---
title: "Magically Disappearing Extensions"
date: 2005-09-08 10:28
status: published
description: >
  Warning: this entry contains Mozilla-related minutiæ... or Mozillinutiæ if you will.

tags: Mozilla, Aviary 1.5, add-ons

links:
  - url: https://bugzilla.mozilla.org/show_bug.cgi?id=307517
    title: "Bug 307517"
    description: "Extensions with invalid IDs disappear when upgrading from 1.0 to 1.5"
    rel: related
    type: text/html
  - url: http://kb.mozillazine.org/Dev_:_Extensions_:_Cross-Version_Compatibility_Techniques#Extension_and_Theme_IDs
    title: "Extension and Theme IDs in Aviary 1.5 (MozillaZine KB)"
    rel: related
    type: text/html
  - url: http://developer.mozilla.org/
    title: "Devmo"
    rel: related
    type: text/html

---

<p>
<a href="https://bugzilla.mozilla.org/show_bug.cgi?id=275529" title="Bug 275529 - Extension Manager does not reject invalid GUIDs">Bug 275529</a> was fixed between <abbr title="Firefox and/or Thunderbird">Aviary</abbr> 1.0.x and the <a href="http://www.mozillazine.org/articles/article7287.html" title="Mozilla Firefox 1.5 Beta 1 Release Candidates available for testing (MozillaZine)">imminent 1.5<abbr title="beta">b</abbr>1</a>. It's going to cause lots of fun.
</p>
<p>
To summarise, Aviary 1.0.x and prior would accept any string as an <abbr title="extension or theme">addon</abbr>'s id, but Aviary 1.5.x requires the id to be in one of two specific formats. Novelly, there is <a href="http://developer.mozilla.org/en/docs/Install_Manifests#id">clear documentation, on Devmo</a>; note that letters other than A, B, C, D, E and F (upper- or lowercase) are <em>invalid</em> in <abbr title="globally unique identifiers">GUIDs</abbr>.
</p>
<p>
Users were able to install addons with malformed ids into Aviary 1.0.x. But when upgrading to 1.5.x, the new version will not recognise these addons; they will <em>completely disappear</em> from the extension or theme manager and the application will not attempt to find a compatible version.
</p>
<p>
An addon's id is defined in the <code>&lt;em:id/&gt;</code> element in the addon's <a href="http://developer.mozilla.org/en/docs/Install_Manifests" title="Devmo">install manifest (install.rdf)</a>. You can check it's valid by looking at it, or by trying to install the addon. If the id is invalid, Aviary 1.5b1 will display an <samp>invalid id</samp> error message and refuse to install it. Note that any other installation errors, such as an incompatible version of the application, will take precedence over the invalid id error.
</p>
<p>
Addon authors should update their addons immediately to include a valid id, instruct existing users to uninstall and reinstall the addon, and (optionally) apologise to them for not following the specification properly in the first place.
</p>