We struggled with this issue for few weeks and we finally got it solved.
In our case, we worked on a branch that was merged with all trunk revisions on a daily basis. When we tried to reintegrate it (merge back to trunk) we got this error.
When we tried to merge the missing ranges to our branch we got message that there is nothing to merge. It happened in several unrelated branches and with different files and folders.
The solution was to add the missing ranges to the svn:mergeinfo property of the file or folder in our branch.
For each “Missing ranges: path:revision_range” line in the message you got:
- Edit the svn:mergeinfo property in file/folder mentioned in in
the merged branch - Append the following : string at the end of the property value (e.g. /trunk/images/test:280-324)
- Save the SVN property
Commit all changes and reintegrate again