diff --git a/.github/workflows/packaging.yml b/.github/workflows/packaging.yml
index d53aa82b8..a09540cfe 100644
--- a/.github/workflows/packaging.yml
+++ b/.github/workflows/packaging.yml
@@ -34,7 +34,7 @@ jobs:
       run: python -m build .
     - name: Run twine check
       run: twine check dist/*
-    - uses: actions/upload-artifact@v2
+    - uses: actions/upload-artifact@v4
       with:
         name: tox-gh-actions-dist
         path: dist
diff --git a/docs/changelog.rst b/docs/changelog.rst
index 7f0fe3d06..2ac9650d1 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -9,6 +9,7 @@ These are new features and improvements of note in each release
     :backlinks: top
 
 
+.. include::  whatsnew/v0-5-6.rst
 .. include::  whatsnew/v0-5-5.rst
 .. include::  whatsnew/v0-5-4.rst
 .. include::  whatsnew/v0-5-3.rst
diff --git a/docs/whatsnew/v0-5-6.rst b/docs/whatsnew/v0-5-6.rst
new file mode 100644
index 000000000..4b3473883
--- /dev/null
+++ b/docs/whatsnew/v0-5-6.rst
@@ -0,0 +1,7 @@
+v0.5.6
+------
+
+Bug fixes
+#########
+
+* Update required Pyomo version to allow working with numpy >= 2.0.0.
diff --git a/pyproject.toml b/pyproject.toml
index 60f422d70..d50b4de2e 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -57,9 +57,9 @@ requires-python = ">=3.8"
 dependencies = [
     "blinker",
     "dill",
-    "numpy < 2.0.0",
-    "pandas >= 2.0.0",
-    "pyomo >= 6.6.0, < 7.0",
+    "numpy >= 2.0.0",
+    "pandas >= 2.2.0",
+    "pyomo >= 6.8.0",
     "networkx",
     "oemof.tools >= 0.4.3",
     "oemof.network >= 0.5.0",
diff --git a/src/oemof/solph/__init__.py b/src/oemof/solph/__init__.py
index 7f58c9578..b275f6168 100644
--- a/src/oemof/solph/__init__.py
+++ b/src/oemof/solph/__init__.py
@@ -1,4 +1,4 @@
-__version__ = "0.5.5"
+__version__ = "0.5.6a1"
 
 from . import buses
 from . import components
diff --git a/src/oemof/solph/_energy_system.py b/src/oemof/solph/_energy_system.py
index 79681ad04..51f02dc35 100644
--- a/src/oemof/solph/_energy_system.py
+++ b/src/oemof/solph/_energy_system.py
@@ -302,13 +302,5 @@ def create_time_index(
         number = round(hoy / interval)
     if start is None:
         start = f"1/1/{year}"
-    try:
-        time_index = pd.date_range(
-            start, periods=number + 1, freq=f"{interval}h"
-        )
-    except ValueError:
-        # Pandas <2.2 compatibility
-        time_index = pd.date_range(
-            start, periods=number + 1, freq=f"{interval}H"
-        )
+    time_index = pd.date_range(start, periods=number + 1, freq=f"{interval}h")
     return time_index
diff --git a/src/oemof/solph/_plumbing.py b/src/oemof/solph/_plumbing.py
index 77c8ffb09..07e6a4517 100644
--- a/src/oemof/solph/_plumbing.py
+++ b/src/oemof/solph/_plumbing.py
@@ -30,15 +30,15 @@ def sequence(iterable_or_scalar):
     --------
     >>> y = sequence([1,2,3,4,5,6,7,8,9,10,11])
     >>> y[0]
-    1
+    np.int64(1)
 
     >>> y[10]
-    11
+    np.int64(11)
 
     >>> import pandas as pd
     >>> s1 = sequence(pd.Series([1,5,9]))
     >>> s1[2]
-    9
+    np.int64(9)
 
     >>> x = sequence(10)
     >>> x[0]
diff --git a/src/oemof/solph/flows/_flow.py b/src/oemof/solph/flows/_flow.py
index 6ed8e97ab..2189512f2 100644
--- a/src/oemof/solph/flows/_flow.py
+++ b/src/oemof/solph/flows/_flow.py
@@ -111,7 +111,7 @@ class Flow(Edge):
     >>> f.variable_costs[2]
     5
     >>> f.fix[2]
-    4
+    np.int64(4)
 
     Creating a flow object with time-depended lower and upper bounds: