Mattermost can't display and download images and files

Dear support team,
I have installed Mattermost version 5.29 at Ubuntu 16.04 LTS. I have followed the user guide. Please refer to https://docs.mattermost.com/install/install-ubuntu-1604.html . MySql version is 5.7.32. After installing, restoring backup and starting Mattermost, all the messages can display correctly. However, the images and files can’t display and download. In the file path /opt/mattermost/data file path, it can display images and files. Please refer to the attachment.

Hello, @Ada

Would you mind sharing how does the directory ownership in the /opt/mattermost/ directory looks like?

Please run the sudo chown -R mattermost:mattermost /opt/mattermost and refresh the client again to confirm that you are able to see the images and files again as well as download them.

If that does not help, can you confirm that your System Console > Environment > File Storage is set correctly?

Let me know how it goes. Thanks.

Dear @ahmaddanial,
I would like to inform you that I can be able to see the images and files again as well as download them at Mattermost.
Also, the directory ownership in the /opt/mattermost/ directory looks like show as attachment.
Screenshot from 2020-11-20 10-22-20
Moreover, I would like to ask whether you can find ways to solve the problems at Mattermost send email notification problems . I have the same problem of using Mattermost at Ubuntu 16.04 LTS. I use the same config.json as above question. Thank you.