EC2 Boot & Kernel Diagnostic Troubleshooter
Use the interactive troubleshooter below to identify your EC2 boot or kernel error by symptom, review the raw error log, understand the root cause, and apply the recommended fix.
🚨 Step 1: What specific error symptom are you experiencing?
Please click the most accurate description:
Quick Reference Table
| # | Scenario | Key Error Signal | Root Cause | The Fix |
|---|---|---|---|---|
| 1 | Kernel and AMI mismatch causing kernel panic. | FATAL: kernel too old | Incompatible kernel and userland. | N/A |
| 2 | Missing kernel modules dropping to initramfs shell. | FATAL: Could not load /lib/modules/ | Missing ramdisk, missing correct modules from ramdisk, or Amazon EBS root volume not correctly attached as /dev/sda1. | N/A |
| 3 | EC2 incompatible kernel causing GRUB boot failure. | ERROR Invalid kernel: elf_xen_note_check | Supplied kernel is not supported by GRUB or fallback kernel does not exist. | N/A |
| 4 | File system not found causing fsck failure. | fsck.ext3: No such file or directory | A bug exists in ramdisk filesystem definitions /etc/fstab, misconfigured filesystem definitions in /etc/fstab, or missing/failed drive. | N/A |
| 5 | Root filesystem mismatch leading to VFS kernel panic. | VFS: Unable to mount root fs on unknown-block(8,1) | Hardware device failure on instance store-backed AMI or an EBS volume attachment issue. | Terminate the instance and launch a new instance using a modern kernel. |
| 6 | Root file system/device mismatch dropping to recovery shell. | Root device '/dev/xvda1' doesn't exist | Missing or incorrectly configured virtual block device driver, device enumeration clash, or incorrect choice of instance kernel. | N/A |
| 7 | SELinux misconfiguration triggering enforcing mode halt and kernel panic. | Unable to load SELinux Policy | SELinux has been enabled in error, supplied kernel is not supported by GRUB, or fallback kernel does not exist. | N/A |
| 8 | Xenbus timeout connecting to block devices causing kernel panic. | XENBUS: Timeout connecting to devices! | The block device is not connected to the instance, or this instance is using an old instance kernel. | N/A |