The solution was posted
here by HTYYHRK, but I've also attached a save file inside the library if needed.
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How to Fix the Library Bug (Can't Enter)
OPTION 1
1) Download the '
data' folder attached.
2) Save in front of the Library.
3) Rename the 'www/data' folder in the
game folder to 'data2' and put the
newly downloaded 'data' folder there.
4) Restart the game and walk through the library door.
5) Save and quit.
6) Delete the 'data' folder, and rename 'data2' to 'data' to restore the original files.
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OPTION 2
1) Put the
file17.rar from the attachment into the 'game/save' folder.
2) This save is already inside the library after doing the mentioned fix.
3) Continue the walkthrough in the Library by talking with the Librarian.
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Also I've updated the Walkthrough to v0.5 Part 1 with a 100% Save as well.