Attachment Preview Does not Work After Migration

[Shirley He]

After importing a site backup into a new production machine, we can no longer see previews of attachments. What is strange is that in a previous staging instance in which we performed the same site backup restoration procedure, we can preview the attachments.

We suspect that it may be due to proxies or firewalls, because we had to "substitute" the old production Confluence instance with the new Confluence instance. Could this possibly affected retrieval of file previews? We can see the file thumbnail and we can download it, but previews just won't work.

I found suggestions to enable certain plugins in Confluence, but when I checked, they were all already enabled, so I don't believe it is a plugin problem.

[Diego]

Hello there Shirley! We could first try to access Confluence via localhost and check how the previews behave. Further, could you clarify a few points for us:

1. Is this affecting all types of files?
2. Is this affecting all files?
3. Is this affecting all users?
4. Is this affecting newly attached files?

Also, we could try a reindex from scratch and also rebuild the plugin cache in your new server:

1- Shutdown Confluence
    - Make sure that the process is not running
    - You can check that with ps -aux | grep confluence in Linux and via the Process manager in Windows
2- Go to <confluence-home>
3- Remove the following folders:
    - <confluence-home>/bundled-plugins
    - <confluence-home>/plugins-cache
    - <confluence-home>/plugins-osgi-cache
    - <confluence-home>/plugins-temp
    - <confluence-home>/bundled-plugins_language
    - <confluence-home>/index
    - <confluence-home>/journal
    - <confluence-home>/logs
4- Check permissions for <confluence-home>
    - The user running Confluence must have *full read/write/execute permission on this folder
    - You can use the following commands to set this. Keep in mind that the user confluence here is just a placeholder, you must use the user that exists in your system
    - sudo chown -R confluence:confluence /path/to/<confluence-home>
    - chmod -R u=rwx,g=rx,o=rx /path/to/<confluence-home>
5- Check permissions for <confluence-install>
    - The user running Confluence must have *full read/write/execute permission on this folder
    - You can use the following commands to set this. Keep in mind that the user confluence here is just a placeholder, you must use the user that exists in your system
    - sudo chown -R confluence:confluence /path/to/<confluence-install>
    - chmod -R u=rwx,g=rx,o=rx /path/to/<confluence-install>
6- Start Confluence
7- Click *Cog Icon>General Configuration*
8- Search for *Content Indexing* in the left menu bar
9- Click the *Rebuild* button

Note:

- schedule a instance downtime for this procedure to be executed. Users accessing the instance can hinder the reindex process.

Let us know your thoughts!