Google Compute Engine：/syslinux/vmlinuz.A 具有无效签名

Question

自上周以来，我的 Google Compute Engine 实例由于此错误而无法启动。

[0m[37m[40m[0m[30m[40m[2J[01;01H[0m[37m[40m  Booting `verified image A'



error: /syslinux/vmlinuz.A has invalid signature.



Press any key to continue...



  Failed to boot both default and fallback entries.

有人知道这次失败的原因吗？