VCL Unicode Support

Unicode strings in VCL forms are supported from VCL version 6. The VCL > Unicode Support page of the properties sets how Localizer writes the strings of DFM forms.

Mode

Auto — Localizer detects the mode while reading the form and keeps the result. If it detects Off, Output says so; if your forms use Unicode strings, set the mode to On.
On — strings are written as Unicode.
Off — strings are written in the code page of the target language. Use it only for applications built with VCL versions before 6.

With Off, a translation that contains characters outside the code page is reported, and the form is not written. Change the mode to On or remove the characters.