ValueError: PEFT backend is required for this method.

根据异常栈发现USE_PEFT_BACKEND是False导致的

if not USE_PEFT_BACKEND:
   raise ValueError("PEFT backend is required for this method.")

找到定义此变量文件，PEFT >=0.6 and transformers >= 4.34.0

解决方法 升级包

pip install  -U PEFT  transformers