I was editing my wiki page. When I clicked on the Save button, the browser showed that it was still submitting after waiting for a minute. Then, I clicked more on the Save button but to no avail. Then, I realized that there is no more disk space and it was running on page memory. I proceed to clear some space.
As a result, my Dokuwiki page is locked by an external edit and it is showing a blank page. However, when I change that page in edit mode, the content is still there.
Solution
I clear the cache/ folder.
# Note: Use the commands below with care. # It will delete all files. So, backup first. ( cd ./data/cache; find . -type f -name '*.*' -exec rm -f {} \; )