Error: no RPC connection" when trying to run Bitcoin Core functional tests #28000

Motivation

I'm getting a strange error running tests under /src/test/functional/ with the following error:

Temporary test directory at /tmp/test_runner_₿_🏃_20220504_123152
Running Unit Tests for Test Framework Modules
..........
----------------------------------------------------------------------
Ran 10 tests in 0.614s

OK
Traceback (most recent call last):
  File "/usr/src/bitcoin/test/functional/create_cache.py", line 27, in <module>
    CreateCache().main()
  File "/usr/src/bitcoin/test/functional/test_framework/test_framework.py", line 156, in main
    exit_code = self.shutdown()
  File "/usr/src/bitcoin/test/functional/test_framework/test_framework.py", line 311, in shutdown
    self.stop_nodes()
  File "/usr/src/bitcoin/test/functional/test_framework/test_framework.py", line 567, in stop_nodes
    node.stop_node(wait=wait, wait_until_stopped=False)
  File "/usr/src/bitcoin/test/functional/test_framework/test_node.py", line 336, in stop_node
    self.stop(wait=wait)
  File "/usr/src/bitcoin/test/functional/test_framework/test_node.py", line 184, in __getattr__
    assert self.rpc_connected and self.rpc is not None, self._node_msg("Error: no RPC connection")
AssertionError: [node 0] Error: no RPC connection
2022-05-04T19:31:53.315000Z TestFramework (INFO): Initializing test directory /tmp/test_runner_₿_🏃_20220504_123152/cache
2022-05-04T19:31:56.079000Z TestFramework (ERROR): Unexpected exception caught during testing
Traceback (most recent call last):
  File "/usr/src/bitcoin/test/functional/test_framework/test_framework.py", line 132, in main
    self.setup()
  File "/usr/src/bitcoin/test/functional/test_framework/test_framework.py", line 294, in setup
    self.setup_chain()
  File "/usr/src/bitcoin/test/functional/test_framework/test_framework.py", line 385, in setup_chain
    self._initialize_chain()
  File "/usr/src/bitcoin/test/functional/test_framework/test_framework.py", line 777, in _initialize_chain
    self.start_node(CACHE_NODE_ID)
  File "/usr/src/bitcoin/test/functional/test_framework/test_framework.py", line 534, in start_node
    node.wait_for_rpc_connection()
  File "/usr/src/bitcoin/test/functional/test_framework/test_node.py", line 225, in wait_for_rpc_connection
    raise FailedToStartError(self._node_msg(
test_framework.test_node.FailedToStartError: [node 0] bitcoind exited with status 3 during initialization
2022-05-04T19:31:56.133000Z TestFramework (INFO): Stopping nodes
[node 0] Cleaning up leftover process
Traceback (most recent call last):
  File "test/functional/test_runner.py", line 832, in <module>
    main()
  File "test/functional/test_runner.py", line 471, in main
    run_tests(
  File "test/functional/test_runner.py", line 525, in run_tests
    subprocess.check_output([sys.executable, tests_dir + 'create_cache.py'] + flags + ["--tmpdir=%s/cache" % tmpdir])
  File "/usr/lib/python3.8/subprocess.py", line 415, in check_output
    return run(*popenargs, stdout=PIPE, timeout=timeout, check=True,
  File "/usr/lib/python3.8/subprocess.py", line 516, in run
    raise CalledProcessError(retcode, process.args,
subprocess.CalledProcessError: Command '['/usr/bin/python3', '/usr/src/bitcoin/test/functional/create_cache.py', '--cachedir=/usr/src/bitcoin/test/cache', '--configfile=/usr/src/bitcoin/test/functional/../config.ini', '--tmpdir=/tmp/test_runner_₿_🏃_20220504_123152/cache']' returned non-zero exit status 1.
`\

any pointers are highly appreciated

Possible solution

No response

Useful Skills

• RPC/P2P layer
• Debugging
• overall understanding of Bitcoin Core

Guidance for new contributors

Want to work on this issue?

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Can you try with:

diff --git a/test/functional/test_framework/test_node.py b/test/functional/test_framework/test_node.py
index 5111d88e15..1e605e00b8 100755
--- a/test/functional/test_framework/test_node.py
+++ b/test/functional/test_framework/test_node.py
@@ -232,6 +232,8 @@ class TestNode():
         poll_per_s = 4
         for _ in range(poll_per_s * self.rpc_timeout):
             if self.process.poll() is not None:
+                self.stderr.seek(0)
+                print(self.stderr.read())
                 raise FailedToStartError(self._node_msg(
                     'bitcoind exited with status {} during initialization'.format(self.process.returncode)))
             try:

Let us know if this is still an issue