U盘安装debian bullseye时，启动时错误 boot：no configuration found.

从deiban.org下载DVD镜像，使用UltraIso工具记录到U盘，插入到电脑上安装时发生错误，无法启动。

提示： boot：no configuration found.

解决方法：
修改U盘中的这几个文件夹或文件名：

文件夹：
isolinux –> syslinux
以下2个文件位于原来的isolinux文件夹中：
isolinux.bin –> syslinux.bin
isolinux.cfg –> syslinux.cfg
然后把U盘重新插入电脑，就可以启动了。
另外，可以尝试使用其他的写盘工具，比如:Universal-USB-Installer等。
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参考: https://askubuntu.com/questions/329704/syslinux-no-default-or-ui-configuration-directive-found
Generally the iso image that are intended to be burned and booted from CD/DVD has all the files required for boot in the isolinux folder. Whereas the iso images that are intended to be run from USB has all the files required for boot in the syslinux folder. So when you try to burn and boot a CD/DVD iso from USB, it cannot recognize the type of boot medium as it will not have syslinux folder it will simply give Boot failure : No DEFAULT or UI configuration directive found!.

General solution for the Error

Open the USB installation media, then rename the following:
isolinux –> syslinux (folder)
isolinux.bin –> syslinux.bin
isolinux.cfg –> syslinux.cfg
The system looks for these two files (.bin & .cfg) in the syslinux folder at root of the device. So make sure you have both files in the syslinux folder.
source: http://www.geekzground.com/index/?p=27
same: http://techie-buzz.com/how-to/syslinux-no-default-ui-error-fix.html
http://www.syslinux.org/archives/2010-October/015756.html