diff --git a/README.md b/README.md
index 33d1dc3ee..4367c6b07 100644
--- a/README.md
+++ b/README.md
@@ -555,6 +555,8 @@ It's important to note that after one or more candidate jobs are unblocked (eith
 
 When using `discard` as the behaviour to handle conflicts, you might have jobs discarded for until the `duration` interval if something happens and a running job fails to release the semaphore.
 
+If a job's class no longer exists by the time its concurrency controls are checked—say it was renamed or removed in a deploy while jobs referencing it were still in the queue—the job is marked as failed with a `SolidQueue::Job::ClassMissingError`, so it shows up in [failed jobs](#failed-jobs-and-retries), where it can be retried once the class is back, or discarded. Jobs with a missing class picked up by a worker fail with the same error.
+
 
 For example:
 ```ruby
diff --git a/app/models/solid_queue/blocked_execution.rb b/app/models/solid_queue/blocked_execution.rb
index 68551a5f5..a84660a46 100644
--- a/app/models/solid_queue/blocked_execution.rb
+++ b/app/models/solid_queue/blocked_execution.rb
@@ -46,7 +46,12 @@ def releasable(concurrency_keys)
     def release
       SolidQueue.instrument(:release_blocked, job_id: job.id, concurrency_key: concurrency_key, released: false) do |payload|
         transaction do
-          if acquire_concurrency_lock
+          if job.job_class.nil?
+            job.failed_with(Job::ClassMissingError.for(job))
+            destroy!
+
+            payload[:failed] = true
+          elsif acquire_concurrency_lock
             promote_to_ready
             destroy!
 
@@ -58,7 +63,8 @@ def release
 
     private
       def set_expires_at
-        self.expires_at = job.concurrency_duration.from_now
+        duration = job.job_class ? job.concurrency_duration : SolidQueue.default_concurrency_control_period
+        self.expires_at = duration.from_now
       end
 
       def acquire_concurrency_lock
diff --git a/app/models/solid_queue/claimed_execution.rb b/app/models/solid_queue/claimed_execution.rb
index 90b56b42b..4b39c8c10 100644
--- a/app/models/solid_queue/claimed_execution.rb
+++ b/app/models/solid_queue/claimed_execution.rb
@@ -115,6 +115,8 @@ def finalizing
       end
 
       def execute
+        raise Job::ClassMissingError.for(job) if job.job_class.nil?
+
         ActiveJob::Base.execute(job.arguments.merge("provider_job_id" => job.id))
         Result.new(true, nil)
       rescue Exception => e
diff --git a/app/models/solid_queue/job.rb b/app/models/solid_queue/job.rb
index 49b47bb91..cb8f25bee 100644
--- a/app/models/solid_queue/job.rb
+++ b/app/models/solid_queue/job.rb
@@ -4,6 +4,15 @@ module SolidQueue
   class Job < Record
     class EnqueueError < StandardError; end
 
+    # Raised when a job's class can't be resolved anymore, typically because it
+    # was renamed or removed in a deploy while jobs referencing it were in
+    # flight. It subclasses NameError, which is what resolving the class raises.
+    class ClassMissingError < NameError
+      def self.for(job)
+        new("Job class #{job.class_name.inspect} could not be resolved")
+      end
+    end
+
     include Executable, Clearable, Recurrable, Batchable
 
     serialize :arguments, coder: JSON
diff --git a/app/models/solid_queue/job/concurrency_controls.rb b/app/models/solid_queue/job/concurrency_controls.rb
index 30d4399ed..b59c464ad 100644
--- a/app/models/solid_queue/job/concurrency_controls.rb
+++ b/app/models/solid_queue/job/concurrency_controls.rb
@@ -33,6 +33,10 @@ def blocked?
         blocked_execution.present?
       end
 
+      def job_class
+        @job_class ||= class_name.safe_constantize
+      end
+
       private
         def concurrency_on_conflict
           job_class.concurrency_on_conflict.to_s.inquiry
@@ -66,10 +70,6 @@ def release_next_blocked_job
           BlockedExecution.release_one(concurrency_key)
         end
 
-        def job_class
-          @job_class ||= class_name.safe_constantize
-        end
-
         def execution
           super || blocked_execution
         end
diff --git a/lib/solid_queue/log_subscriber.rb b/lib/solid_queue/log_subscriber.rb
index 6806b853e..fd4f54fd0 100644
--- a/lib/solid_queue/log_subscriber.rb
+++ b/lib/solid_queue/log_subscriber.rb
@@ -59,7 +59,7 @@ def release_many_blocked(event)
   end
 
   def release_blocked(event)
-    debug formatted_event(event, action: "Release blocked job", **event.payload.slice(:job_id, :concurrency_key, :released))
+    debug formatted_event(event, action: "Release blocked job", **event.payload.slice(:job_id, :concurrency_key, :released, :failed))
   end
 
   def enqueue_recurring_task(event)
diff --git a/test/models/solid_queue/blocked_execution_test.rb b/test/models/solid_queue/blocked_execution_test.rb
new file mode 100644
index 000000000..8586edb5d
--- /dev/null
+++ b/test/models/solid_queue/blocked_execution_test.rb
@@ -0,0 +1,52 @@
+# frozen_string_literal: true
+
+require "test_helper"
+
+class SolidQueue::BlockedExecutionTest < ActiveSupport::TestCase
+  self.use_transactional_tests = false
+
+  class NonOverlappingJob < ApplicationJob
+    limits_concurrency key: ->(job_result, **) { job_result }
+
+    def perform(job_result)
+    end
+  end
+
+  setup do
+    @result = JobResult.create!(queue_name: "default")
+  end
+
+  teardown do
+    SolidQueue::Job.destroy_all
+    SolidQueue::Semaphore.delete_all
+    JobResult.delete_all
+  end
+
+  test "release marks the job as failed and destroys the blocked row when the job class no longer resolves" do
+    # Enqueue and consume the semaphore so the next job blocks.
+    NonOverlappingJob.perform_later(@result)
+    blocking_job = SolidQueue::Job.last
+    NonOverlappingJob.perform_later(@result)
+    blocked_job = SolidQueue::Job.last
+    blocked = blocked_job.blocked_execution
+    assert blocked, "expected the second job to be blocked"
+
+    # Simulate the class being renamed/removed between deploys
+    blocked_job.update_columns(class_name: "GoneJob")
+
+    assert_difference -> { SolidQueue::BlockedExecution.count } => -1,
+                     -> { SolidQueue::FailedExecution.count } => 1 do
+      assert_nothing_raised do
+        blocked.reload.release
+      end
+    end
+
+    # No ready execution was promoted — the orphan is now surfaced as a failed execution.
+    assert_nil SolidQueue::ReadyExecution.find_by(job_id: blocked_job.id)
+
+    failed = SolidQueue::FailedExecution.find_by(job_id: blocked_job.id)
+    assert failed, "expected a failed execution to be created for the orphan"
+    assert_equal "SolidQueue::Job::ClassMissingError", failed.exception_class
+    assert_match "GoneJob", failed.message
+  end
+end
diff --git a/test/models/solid_queue/claimed_execution_test.rb b/test/models/solid_queue/claimed_execution_test.rb
index 01242883c..b09fdeb90 100644
--- a/test/models/solid_queue/claimed_execution_test.rb
+++ b/test/models/solid_queue/claimed_execution_test.rb
@@ -146,7 +146,7 @@ class SolidQueue::ClaimedExecutionTest < ActiveSupport::TestCase
     claimed_execution = claim_job(job)
 
     assert_difference -> { SolidQueue::ClaimedExecution.count } => -1, -> { SolidQueue::FailedExecution.count } => 1 do
-      assert_raises NameError do
+      assert_raises SolidQueue::Job::ClassMissingError do
         claimed_execution.perform
       end
     end
@@ -159,7 +159,7 @@ class SolidQueue::ClaimedExecutionTest < ActiveSupport::TestCase
     claimed_execution = claim_job(job)
 
     assert_difference -> { SolidQueue::ClaimedExecution.count } => -1, -> { SolidQueue::FailedExecution.count } => 1 do
-      assert_raises NameError do
+      assert_raises SolidQueue::Job::ClassMissingError do
         claimed_execution.perform
       end
     end