From 566164a321afb2109b5f8a87bcc534d8d40aa2df Mon Sep 17 00:00:00 2001
From: Tim Gross <tgross@hashicorp.com>
Date: Thu, 2 Oct 2025 12:24:59 -0400
Subject: [PATCH] state: nil-check waiting evals before attempting to cancel
 them (#26872)

When we attempt to drop unneeded evals from the eval broker, if the eval has
been GC'd before the check is made, we hit a nil pointer. Check that the eval
actually exists before attempting to remove it from the broker.

Fixes: https://github.com/hashicorp/nomad/issues/26871
---
 .changelog/26872.txt | 3 +++
 nomad/fsm.go         | 2 +-
 2 files changed, 4 insertions(+), 1 deletion(-)
 create mode 100644 .changelog/26872.txt

diff --git a/.changelog/26872.txt b/.changelog/26872.txt
new file mode 100644
index 000000000..3a5163435
--- /dev/null
+++ b/.changelog/26872.txt
@@ -0,0 +1,3 @@
+```release-note:bug
+state: Fixed a bug where the server could panic when attempting to remove unneeded evals from the eval broker
+```
diff --git a/nomad/fsm.go b/nomad/fsm.go
index c760b5caf..89b813c98 100644
--- a/nomad/fsm.go
+++ b/nomad/fsm.go
@@ -1034,7 +1034,7 @@ func (n *nomadFSM) applyAllocClientUpdate(msgType structs.MessageType, buf []byt
 				"eval_id", evalID, "error", err)
 			return err
 		}
-		if !eval.ShouldEnqueue() {
+		if eval != nil && !eval.ShouldEnqueue() {
 			n.evalBroker.DropWaiting(eval)
 		}
 	}