要約

After upgrading Confluence, attachment thumbnails may stop working. 

環境

7.4.7

診断

An error like this will appear in the logs:

2021-03-11 16:26:06,730 WARN [http-nio-8090-exec-15 url:/confluence/res...vertHD/185993966/1 username:xxxxxxxx] [plugins.conversion.impl.FileSystemConversionState] markAsError Creating error file: /data/confluence/dcl-document_hd/214/243/185993964/185993966_1.err
 -- referer: 

原因

Confluence uses a file format similar to the one described in our Hierarchical File System Attachment Storage kb article to store attachment thumbnails in the dcl-thumbnail directory. Specifically, we use this format:
dcl-thumbnail/<last 3 digits of page id % 250>/<next to last 3 digits of page id % 250>/<full page id>/<attachmentid>_<version>

So in this example the page id for this thumbnail:
dcl-thumbnail/160/243/185993660/185993714_1.err

would be 185993660 and the attachment id would be 185993714.

Once a .err extension is added to the end of the file, the thumbnail will no longer appear in the UI. 

ソリューション

You can simply delete the .err file and then refresh the page, and Confluence will create a new thumbnail file and the thumbnail should show up in the UI again. You can also run these commands:

find . -name "*.err" -type f
find . -name "*.err" -type f -delete

from the dcl-thumbnail directory to delete the .err files in bulk. The first one should give you a dry run of the files to be deleted and the second would delete the files.