An error?

[bsdun]

I have an old computer, where I rarely test some stuff. Today upon boot I got strange error. After rebooting the error is gone. What does it mean?

[jggimi]

This type of error is called a kernel panic. You can tell because it is a message from the kernel (blue background, white letters) that starts with the word "panic:" followed by the type of panic. This states "pool_do_get: anonpl free list modified..." and additional information. We can see that the process that was running was slaacd(8), the IPv6 autoconfiguration daemon, and then we can see the start of the stack trace, followed by entry into the kernel debugger ddb(4).

I can't tell you much about the panic from the photograph you attached. I ran find(1) with grep(1) on the kernel source code to discover the pool_do_get function is part of /usr/src/sys/kern/subr_pool.c, the memory pool resource management module, but I haven't looked through the code at all.

I have two small pieces of advice:

1. The crash(8) man page can give you guidance on what to do if this problem repeats.
2. Run syspatch(8) to update this system. If I counted right, you're missing up to 11 published errata patches, including several kernel patches.