Chang'an (805) — the same event in Old Book of Tang and Zizhi Tongjian

Old Book of Tang: Emperor Dezong died at the age of 64 at Huining Hall.; Zizhi Tongjian: Emperor Dezong dies.

What each source says

Old Book of Tang (Jiu Tangshu), Annals · AD 805 · 長安

Emperor Dezong died at the age of 64 at Huining Hall.

是日，上崩於會寧殿，享壽六十四。
Location: 舊唐書 卷13 貞元21年 1月

Zizhi Tongjian (Comprehensive Mirror) · AD 805 · 長安

Emperor Dezong dies.

癸已，德宗崩。
Location: 資治通鑑 卷236

Place: 長安

Show on the map — open Old Book of Tang (Jiu Tangshu), Annals