Error message 
Autor: Luca F.
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i get this message: an error occured while loading the Project
(There is an error in XML document (0.0)
Posted on the
see if this post helps;
https://helpcenter.websitex5.com/pl/post/133137
Autor
I have tried the suggestion to change library.xml and you need to rename it to old.xml and then rename librarybu.xml to library.xml and then try to open the project again
Does not work
Else try a automaticly made backup from a previous saved project.
This works in v13 and v12, the same as it did in v10;
https://helpcenter.websitex5.com/pl/post/47713
Autor
my back up folder on this project is empty - but I can see all the file created so far in the folder preview - the project not published on line because not completed
In that case I am afraid you will need to start over again.
Make backup's from time to time, especially after a lot of changes in step 5 export project and save it on another medium then where x5 is.