diff --git a/pyproject.toml b/pyproject.toml
index ccf91a3e5..2c2e4b15e 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -55,7 +55,7 @@ dependencies = [
 [project.optional-dependencies]
 # Interactive network visualization with enhanced color picker
 network_viz = [
-    "dash >= 3.0.0, < 4",
+    "dash >= 3.0.0, < 5",
     "dash-cytoscape >= 1.0.0, < 2",
     "dash-daq >= 0.6.0, < 1",
     "networkx >= 3.0.0, < 4",
@@ -69,7 +69,7 @@ full = [
     "pyvis==0.3.2",  # Visualizing FlowSystem Network
     "scipy >= 1.15.1, < 2", # Used by tsam. Prior versions have conflict with highspy. See https://github.com/scipy/scipy/issues/22257
     "gurobipy >= 10.0.0, < 14; python_version < '3.14'",  # No Python 3.14 wheels yet (expected Q1 2026)
-    "dash >= 3.0.0, < 4",  # Visualizing FlowSystem Network as app
+    "dash >= 3.0.0, < 5",  # Visualizing FlowSystem Network as app
     "dash-cytoscape >= 1.0.0, < 2",  # Visualizing FlowSystem Network as app
     "dash-daq >= 0.6.0, < 1",  # Visualizing FlowSystem Network as app
     "networkx >= 3.0.0, < 4",  # Visualizing FlowSystem Network as app
@@ -90,7 +90,7 @@ dev = [
     "scipy==1.16.3",  # 1.16.1+ required for Python 3.14 wheels
     "highspy==1.13.1",  # Latest known-good. Bump once HiGHS#2975 fix ships in 1.14.1+
     "gurobipy==12.0.3; python_version < '3.14'",  # No Python 3.14 wheels yet
-    "dash==3.3.0",
+    "dash==4.2.0",
     "dash-cytoscape==1.0.2",
     "dash-daq==0.6.0",
     "networkx==3.0.0",