/saml2/login Error

[TimH04]

Hello guys
We are going to use your library in our django project. Now we found a bug with the /saml2/login function.
On a local environment the saml2 signing works but on our kubernetes cluster we get an error.
But the error is just a "standard" error and does not provide information how to fix problem.
We are using the Alpine 3.17 Base Image and installed xmlsec and xmlsec-dev. The environment should be mostly the same.
The Djangosaml2version is 1.9.3.

Error

['/usr/bin/xmlsec1', '--sign', '--privkey-pem', '/app/backend/certificate/key_certificate.key', '--id-attr:ID', 'urn:oasis:names:tc:SAML:2.0:protocol:AuthnRequest', '--node-id', 'id-UKNHXCEIiZusmqSbT', '--output', '/tmp/tmp750au002.xml', '--lax-key-search', '/tmp/tmp9__60ipk.xml']`
saml2.sigver.XmlsecError: returncode=1
error=Signature status: ERROR
Error: failed to sign file "/tmp/tmp9__60ipk.xml"
output=


The above exception was the direct cause of the following exception:

Traceback (most recent call last):

File "/usr/local/lib/python3.12/site-packages/django/core/handlers/exception.py", line 55, in inner
    response = get_response(request)
               ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/django/core/handlers/base.py", line 197, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/django/views/generic/base.py", line 104, in view
    return self.dispatch(request, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/django/utils/decorators.py", line 46, in _wrapper
    return bound_method(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/djangosaml2/views.py", line 89, in wrapper
    return csp_handler(view)(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/django/views/generic/base.py", line 143, in dispatch
    return handler(request, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/djangosaml2/views.py", line 367, in get
    session_id, request_xml = client.create_authn_request(
                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/saml2/client_base.py", line 446, in create_authn_request
    msg = self._message(
          ^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/saml2/entity.py", line 588, in _message
    signed_req = self.sign(
                 ^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/saml2/entity.py", line 524, in sign
    return signed_instance_factory(msg, self.sec, to_sign)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/saml2/sigver.py", line 331, in signed_instance_factory
    signed_xml = seccont.sign_statement(signed_xml, node_name=node_name, node_id=nodeid)
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/saml2/sigver.py", line 1695, in sign_statement
    return self.crypto.sign_statement(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/saml2/sigver.py", line 798, in sign_statement
    raise SignatureError(com_list) from e
saml2.sigver.SignatureError: ['/usr/bin/xmlsec1', '--sign', '--privkey-pem', '/app/backend/certificate/key_certificate.key', '--id-attr:ID', 'urn:oasis:names:tc:SAML:2.0:protocol:AuthnRequest', '--node-id', 'id-UKNHXCEIiZusmqSbT', '--output', '/tmp/tmp750au002.xml', '--lax-key-search', '/tmp/tmp9__60ipk.xml'] 

I would appreciate some help or hints about, how to fix it or if there is any workaround that we could use to solve the problem.

I am looking forward for any help.

Kind regards