intermittent issue in wallet_assumeutxo.py, line 251, assert_equal(chainstates[0]['blocks'], START_HEIGHT) , AssertionError: not(211 == 199) #34710

Is the failure here related to this?

396/455 - wallet_assumeutxo.py failed, Duration: 2 s

stdout:
2026-02-28T16:12:48.637327Z TestFramework (INFO): PRNG seed is: 3704802399065086238
2026-02-28T16:12:48.637849Z TestFramework (INFO): Initializing test directory /Users/runner/work/bitcoin/bitcoin/repo_archive/ci/scratch/test_runner/test_runner_₿_🏃_20260228_155759/wallet_assumeutxo_58
2026-02-28T16:12:49.548117Z TestFramework (INFO): -- Testing assumeutxo
2026-02-28T16:12:49.548768Z TestFramework (INFO): Creating a UTXO snapshot at height 299
2026-02-28T16:12:49.895968Z TestFramework (INFO): Loading snapshot into second node from /Users/runner/work/bitcoin/bitcoin/repo_archive/ci/scratch/test_runner/test_runner_₿_🏃_20260228_155759/wallet_assumeutxo_58/node0/regtest/utxos.dat
2026-02-28T16:12:49.911552Z TestFramework (INFO): Backup from the snapshot height can be loaded during background sync
2026-02-28T16:12:49.915983Z TestFramework (INFO): Backup from before the snapshot height can't be loaded during background sync
2026-02-28T16:12:49.919539Z TestFramework (INFO): Backup from the snapshot height can be loaded during background sync (pruned node)
2026-02-28T16:12:49.940587Z TestFramework (INFO): Backup from before the snapshot height can't be loaded during background sync (pruned node)
2026-02-28T16:12:49.944432Z TestFramework (INFO): Test loading descriptors during background sync
2026-02-28T16:12:49.956406Z TestFramework (INFO): Test that rescanning blocks from before the snapshot fails when blocks are not available from the background sync yet
2026-02-28T16:12:49.956860Z TestFramework (INFO): Restarting node to stop at height 359
2026-02-28T16:12:50.947949Z TestFramework (INFO): Restarted node before snapshot validation completed, reloading...
2026-02-28T16:12:51.316321Z TestFramework (INFO): Verify node state after restart during background sync
2026-02-28T16:12:51.316847Z TestFramework (ERROR): Unexpected exception:
Traceback (most recent call last):
  File "/Users/runner/work/bitcoin/bitcoin/repo_archive/test/functional/test_framework/test_framework.py", line 142, in main
    self.run_test()
    ~~~~~~~~~~~~~^^
  File "/Users/runner/work/bitcoin/bitcoin/repo_archive/ci/scratch/build-aarch64-apple-darwin24.6.0/test/functional/wallet_assumeutxo.py", line 251, in run_test
    assert_equal(chainstates[0]['blocks'], START_HEIGHT)
    ~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/runner/work/bitcoin/bitcoin/repo_archive/test/functional/test_framework/util.py", line 80, in assert_equal
    raise AssertionError("not(%s)" % " == ".join(str(arg) for arg in (thing1, thing2) + args))
AssertionError: not(211 == 199)
2026-02-28T16:12:51.382295Z TestFramework (INFO): Not stopping nodes as test failed. The dangling processes will be cleaned up later.
2026-02-28T16:12:51.382372Z TestFramework (WARNING): Not cleaning up dir /Users/runner/work/bitcoin/bitcoin/repo_archive/ci/scratch/test_runner/test_runner_₿_🏃_20260228_155759/wallet_assumeutxo_58
2026-02-28T16:12:51.382410Z TestFramework (ERROR): Test failed. Test logging available at /Users/runner/work/bitcoin/bitcoin/repo_archive/ci/scratch/test_runner/test_runner_₿_🏃_20260228_155759/wallet_assumeutxo_58/test_framework.log
2026-02-28T16:12:51.382488Z TestFramework (ERROR): 
2026-02-28T16:12:51.382577Z TestFramework (ERROR): Hint: Call /Users/runner/work/bitcoin/bitcoin/repo_archive/test/functional/combine_logs.py '/Users/runner/work/bitcoin/bitcoin/repo_archive/ci/scratch/test_runner/test_runner_₿_🏃_20260228_155759/wallet_assumeutxo_58' to consolidate all logs
2026-02-28T16:12:51.382609Z TestFramework (ERROR): 
2026-02-28T16:12:51.382634Z TestFramework (ERROR): If this failure happened unexpectedly or intermittently, please file a bug and provide a link or upload of the combined log.
2026-02-28T16:12:51.382680Z TestFramework (ERROR): https://github.com/bitcoin/bitcoin/issues
2026-02-28T16:12:51.382703Z TestFramework (ERROR): 


stderr:
[node 3] Cleaning up leftover process
[node 2] Cleaning up leftover process
[node 1] Cleaning up leftover process
[node 0] Cleaning up leftover process

Originally posted by @sedited in #34354

Can be reproduced via:

diff --git a/src/node/kernel_notifications.cpp b/src/node/kernel_notifications.cpp
index ab0e5ccb69..49384c10b8 100644
--- a/src/node/kernel_notifications.cpp
+++ b/src/node/kernel_notifications.cpp
@@ -59,6 +59,7 @@ kernel::InterruptResult KernelNotifications::blockTip(SynchronizationState state
 
     uiInterface.NotifyBlockTip(state, index, verification_progress);
     if (m_stop_at_height && index.nHeight >= m_stop_at_height) {
+        LogInfo("Send shutdown signal after reaching stop height");
         if (!m_shutdown_request()) {
             LogError("Failed to send shutdown signal after reaching stop height\n");
         }
diff --git a/src/util/tokenpipe.cpp b/src/util/tokenpipe.cpp
index c982fa6fc4..8f96ac3124 100644
--- a/src/util/tokenpipe.cpp
+++ b/src/util/tokenpipe.cpp
@@ -2,6 +2,7 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 #include <util/tokenpipe.h>
+#include <util/time.h>
 
 #include <bitcoin-build-config.h> // IWYU pragma: keep
 
@@ -58,6 +59,7 @@ int TokenPipeEnd::TokenRead()
     uint8_t token;
     while (true) {
         ssize_t result = read(m_fd, &token, 1);
+        UninterruptibleSleep(10ms);
         if (result < 0) {
             // Failure. Check if the read was interrupted by a signal,
             // in that case retry.

https://github.com/bitcoin/bitcoin/actions/runs/22634054083/job/65591928346?pr=34662#step:9:18738