I worked on "replace.py" and I noticed that while we are working on a txt file containing (plaintext) titles (like A, B, C) separated by line, it shows:
Retrieving 50 pages from wikipedia:ckb. WARNING: Page [[ckb:A]] does not exist on wikipedia:ckb.
That page "A" is actually existing, but there could be a bug that don't let to read/write the first page. It is working on next pages (B and C) perfectly.