Strange.
Possibly some work line is referencing the project.
Try and run consistency check / fix (on admin screen)

Thank you for the reply,
I tried the Admin consistency repair tool,
It detected some errors and claimed that it corrected them.
But the errors concerning work keep coming back everytime i use the error scan and continue to say it's corrected.
(Screenshot attached)

Regards

Maybe you can try and update one activity of the project.
Add some work, remove it.
In some case, this fixes those consolidation issues.

So, I tried to update an activity of the project, didn't change the problem.
I'm not sure that the consistency errors are related to this problem.
In fact, I am working on a test environment, so I restored my db from a backup I did just before I moved the demands and activitys (in order to delete the projects).
I used the check error admin tool, errors were there before and aren't resolving neither.

I am currently not totally getting the meaning of "work" in my error message, like, what can it be if I moved all the demands, activitys, flags ect from the project ?

Regards

EDIT : Or maybe you could try to explain me wich reference it represents in the db ? Idk

I moved the demands and activitys

How did you do this.
Please explain way to do this so that we can try and reproduce.
Better : could you please try and reproduce use case on Demo ?

By "moving activitys and tickets" I mean I used the multiple tool to select all the ticket of the project I wanted to delete.
Then assigned them to the project I want to keep in one click with this tool
(See the screenshot)

OK, I'll try and reproduce.
Thanks for the explanation.