if I change the page title, a semicolon (;) is added at the end as soon as I save my changes.
I testet some titles and found the exakt phrase that throws this error.
Sushi & Grill
This can be saved w/o problems.
This can be saved but it is saved as "Sushi&Grill;" with semicolon at the end.
Hm, I'm pretty sure it is related to HTML entities starting with & and ending with ; because if you replace & with its HTML entity & then it won't append semicolon a the end of the title (but will display & in the page title).