Cannot install add-on on Firefox. Message: file seems to be corrupt.
Asked by Franz Kehl:

The user is not administrator of our license.

I think the data is hosted on our server, but not sure.

Thanks for any help!


Answers:
author: Nic Brough -Adaptavist-
body: We'll need to know what Confluence you are running (the Server version, or if it's Cloud) and what App you're trying to install.

This error happens most when you try to import a Connect App into Server though, so I'm guessing that may be what you've tried.

comments: author: Franz Kehl
body: **Hi, this is what we use:**

**Confluence (Server) 100 Users: Commercial License, SEN-2085157**

**Not sure what you mean by Connect App. We would appreciate practical help - how to solve this - since we will be keep using Confluence.**

**Thank you!**


author: Nic Brough -Adaptavist-
body: Connect Apps are "add-ons" for Cloud systems. Server Apps are for Server.

It looks to me like you have found the connector/link for installing a Connect App and tried to use it as an upload for a Server system.

You cannot install Connect (Cloud) Apps on Server, and you cannot install Server Apps on Cloud.

Could you tell us what App you are trying to install?


author: Franz Kehl
body: I don't think there was an active finding of an App.

Our shared working area is wiki.kek.ch. The user tried to open a document within Wiki/Atlassian to work on it, so it would be automatically updated for everyone who works with our Wiki-platform.

The first message is then: "A plugin is required to use this feature. Would you like to install it?"

The second message is: "The add-on downloaded from this page cannot be installed as it seems to be corrupt."

The photos to these messages are attached.

![add-on cannot be installed.png](https://community.atlassian.com/t5/image/serverpage/image-id/39350iD08192E089C5333C/image-size/large?v=v2&px=999 "add-on cannot be installed.png")![plugin required.png](https://community.atlassian.com/t5/image/serverpage/image-id/39349iEA853223226DFD92/image-size/large?v=v2&px=999 "plugin required.png")


author: Nic Brough -Adaptavist-
body: Ok, so this is something that is not being added via the standard UPM - you already have a plugin that is finding your users trying to do something that requires another plugin to use it, and it's taking them off to try to install it.

I would work from the interception point, rather than guess. What is the document that the user is trying to open? (Not the actual document, but the specific type - word, CAD, pdf, etc)


author: Franz Kehl
body: Excel is the one we are talking about right now. The problem also exists when opening a word-document.


author: Nic Brough -Adaptavist-
body: I'm a little bit lost then, Confluence already has stuff built into it to allow the download and preview of office docs, so there's something not quite right here.

I think the next question is what plugin it is trying to fetch and install.

What version of Confluence are you on? (Should be in the footer, but if not, try Admin -\> System information, or Help -\> About)


author: Franz Kehl
body: * [Atlassian Confluence](http://www.atlassian.com/software/confluence) 5.10.8


author: Nic Brough -Adaptavist-
body: Ok, I was concerned that you might have one too old to support the plugin I think it's asking for, but 5.10 should be fine.

Do you know what App it is trying to install?


author: Franz Kehl
body: Unfortunately not. The person concerned will be back on Thursday with his computer. But the images I sent you earlier are all we are getting as info. If you could give me a hint what to look for, I could try.


author: Franz Kehl
body: Hi Nic

The person concerned is here today. Do you have any suggestions how to check what App his laptop is trying to install?

Thanks.


author: Nic Brough -Adaptavist-
body: It should be in the urls it is trying to hit.


author: Franz Kehl
body: we do not get any other urls than the one in the 1st photo. He works with Firefox.


author: Franz Kehl
body: We found a way to ensure that we have all the versions of an edited document listed in Wiki.

1. Download the file you want to work on

2. Edit it

3. Upload the file again through DRAG-AND-DROP, using the exact same file name as before.

Hope this helps.


author: Sylvain L?ger
body: Same problem.

confluence (local): 6.1.2

firefox 66.0.1


author: Klara Valkova
body: Unfortunately I have the same problem, neither workaround 1 nor workaround 2 didn't help. Is this already solved? Is there any other way how to work in office tools in firefox?


author: Diego
body: Hello there Franz!

The behaviour you are facing and the procedure described makes me believe that the user was trying to use the **Edit in Office** feature.

The situation is better described under this bug report:

**[CONFSERVER-40289 \| WebDAV Launcher Office Connector is broken in Firefox 43.0](https://jira.atlassian.com/browse/CONFSERVER-40289)**

The workarounds provided there are the following:

-----------------------------------------------------------------------------------------

Workaround 1 {#toc-hId-1849788293}
----------------------------------

1. Download the plugin directly from mozilla (using Chrome so it doesn't auto install) [https://addons.mozilla.org/firefox/downloads/file/259818/webdav_launcher-1.0.8-fx.xpi](https://addons.mozilla.org/firefox/downloads/file/259818/webdav_launcher-1.0.8-fx.xpi "Follow link")
2. Go to about:addons, then Cog Menu \> Install Add-On from file and select the .xpi file
3. Click Install on the pop-up box, then Restart

Workaround 2 {#toc-hId--702368668}
----------------------------------

1. Go the location bar and enter about:config
2. Click *I'll be careful, I promise!*
3. In the new Search field at the top enter xpinstall.signatures.required
4. Double click the entry to make it **false**

You can also put this entry in user.js in the firefox profile directory  
**user.js**  

```
user_pref("xpinstall.signatures.required", false);
```

The plugin will now work.

-----------------------------------------------------------------------------------------

A similar behaviour can also appear in **Confluence Cloud** instances. Another customer recently faced this behaviour there:

**[Atlassian Companion Availability \| Atlassian Community](https://community.atlassian.com/t5/Confluence-questions/Atlassian-Companion-Availability/qaq-p/951502)**

Let us know if this helps the user!

comments: author: Franz Kehl
body: Thanks. I will check, may not be today but next week. Will let you know if it works.


author: Franz Kehl
body: I tried.

1. First I disabled the WebDAV launcher in Firefox.

2. Then I tried to download the plugin in Chrome with the link provided in the description. "Page cannot be found". If I search in the search bar of addons.mozilla, I get a WebDAV-version in Russian which I didn't download as everything is in Russian.

3. Then I tried Workaround 2

4. Tried do edit a document in Confluence. Still same messages as before.

How to install the WebDAV launcher again, is there an official version from Mozilla or is it safe to use the Russian version?

Thanks, getting a bit frustrated here.