Summary

You cannot upload a file larger than 2GB through 'Upload file', while you can by Drag & Drop (See also attachmentPage.jpg)

Steps to Reproduce

1. Install vanilla Confluence 5.8.10 using H2SQL (I guess DB does not matter)
2. Configure Attachment Maximum Size to accept up to 10GB
3. Create a space and a page
4. Go to attachment (/pages/viewpageattachments.action?pageId=<PAGE-ID>) of the page
5. Try to upload a file larger than 2GB through 'Upload file'

Expected Results

The file larger than 2GB can be uploaded successfully

Actual Results

• The file larger than 2GB cannot be uploaded. The user will be redirected to /pages/doattachfile.action?pageId=<PAGE-ID>, which does not exist. See also redirect.jpg.
• The below exception is thrown in the atlassian-confluence.log file:

  2015-09-17 09:51:28,383 WARN [http-nio-15810-exec-8] [opensymphony.webwork.dispatcher.ServletDispatcher] getMaxSize Unable to format 'webwork.multipart.maxSize' property setting. Defaulting to Integer.MAX_VALUE
   -- referer: http://<CONFLUENCE_BASE_URL>/pages/viewpageattachments.action?pageId=1572867 | url: /confluence15810/pages/doattachfile.action | userName: admin
  2015-09-17 09:51:33,969 ERROR [http-nio-15810-exec-8] [com.atlassian.xwork.FileUploadUtils] checkMultiPartRequestForErrors java.io.IOException: Content Length Error (2147487387 > 2147483647)
   -- referer: http://<CONFLUENCE_BASE_URL>/pages/viewpageattachments.action?pageId=1572867 | url: /confluence15810/pages/doattachfile.action | userName: admin | action: doattachfile | page: 1572867
  2015-09-17 09:51:34,030 INFO [http-nio-15810-exec-8] [atlassian.confluence.util.AccessLogFilter] doFilter admin POST http://<CONFLUENCE_BASE_URL>/pages/doattachfile.action 625777+58696 5649 0:0:0:0:0:0:0:1
  2015-09-17 09:51:34,039 WARN [http-nio-15810-exec-3] [opensymphony.webwork.dispatcher.ServletDispatcher] getMaxSize Unable to format 'webwork.multipart.maxSize' property setting. Defaulting to Integer.MAX_VALUE
   -- referer: http://<CONFLUENCE_BASE_URL>/pages/viewpageattachments.action?pageId=1572867 | url: /confluence15810/pages/doattachfile.action | userName: admin
  2015-09-17 09:51:39,641 ERROR [http-nio-15810-exec-3] [com.atlassian.xwork.FileUploadUtils] checkMultiPartRequestForErrors java.io.IOException: Content Length Error (2147487387 > 2147483647)
   -- referer: http://<CONFLUENCE_BASE_URL>/pages/viewpageattachments.action?pageId=1572867 | url: /confluence15810/pages/doattachfile.action | userName: admin | action: doattachfile | page: 1572867
  2015-09-17 09:51:39,688 INFO [http-nio-15810-exec-3] [atlassian.confluence.util.AccessLogFilter] doFilter admin POST http://<CONFLUENCE_BASE_URL>/pages/doattachfile.action 683821-22390 5650 0:0:0:0:0:0:0:1
  

Workaround

Use Drag & Drop instead