Broken images after upgrading to 3.6.2

Just upgraded to 3.6.2 using docker images. After the upgrade, the old images in the channels are gone, leaving broken image icons. The console shows the following error:

detailed_error: "There doesn't appear to be an api call for the url='/api/v3/teams/1rk493uf7przzxqw5khmiz9y5y/files/get/kzn7eh7xjiyo7cdbrettjf489e/texpnrfryfbz8pat54ohmtjcea/5pw79fy8mtfq5x189qye8spu3r/web-na-peterson.JPG'.  Typo? are you missing a team_id or user_id as part of the url?"
id: "api.context.404.app_error"
message: "Sorry, we could not find the page."
status_code: 404

However, when I logged onto the server and check the file, it is there and readable:

root@012a5cf0dbf8:/# file /mattermost/data/teams/1rk493uf7przzxqw5khmiz9y5y/channels/kzn7eh7xjiyo7cdbrettjf489e/users/texpnrfryfbz8pat54ohmtjcea/5pw79fy8mtfq5x189qye8spu3r/web-na-peterson.JPG
/mattermost/data/teams/1rk493uf7przzxqw5khmiz9y5y/channels/kzn7eh7xjiyo7cdbrettjf489e/users/texpnrfryfbz8pat54ohmtjcea/5pw79fy8mtfq5x189qye8spu3r/web-na-peterson.JPG: JPEG image data, JFIF standard 1.02

root@012a5cf0dbf8:/# ls -l /mattermost/data/teams/1rk493uf7przzxqw5khmiz9y5y/channels/kzn7eh7xjiyo7cdbrettjf489e/users/texpnrfryfbz8pat54ohmtjcea/5pw79fy8mtfq5x189qye8spu3r/web-na-peterson.JPG
-rw-r--r--. 1 root root 6173 Nov 21 10:03 /mattermost/data/teams/1rk493uf7przzxqw5khmiz9y5y/channels/kzn7eh7xjiyo7cdbrettjf489e/users/texpnrfryfbz8pat54ohmtjcea/5pw79fy8mtfq5x189qye8spu3r/web-na-peterson.JPG

I can post new images and they are displayed without any error. In the console, it seems it is issuing different api calls for the new image:

/api/v3/teams/1rk493uf7przzxqw5khmiz9y5y/channels/kzn7eh7xjiyo7cdbrettjf489e/posts/q8ma8p3iwpre7bgad5njkfztsc/get_file_infos

/api/v3/files/w5s6dyq31i8gpnsj4efcd4fxje/get_thumbnail

Any advice? Thanks.