Trying to Change Validated End Date and Receive Technical Issue occurred

I cannot explain but I fixed this issue. I found that there a few notes on the activity that had no user name attach to it and in the database these notes were showing a value of 0 in the idle column.

I correct the user id manually and changed the values to 1 and the problem was fixed.
I am not sure what the idle column does but this seemed to fix the problem.

Will do, however can you explain when you say

Maybe if you could look at history of element, you could check when the note was saved and what may have occured.

Do you mean in the Database? If YES, what is the name of the table/column

If you mean somewhere else, please advise of its exact location.

I did what you said and the history of the activity shows the date and times to be correct and does not show any errors. It seems correct the History Log of the activity. The only thing is that I did find that the notes where I had to change the idle value, they do not have a username in the username column. They are blank in this cell for those notes.

Could this have been the problem?