Drop support for marshmallow 3

Author: sloria

.github/workflows/build-release.yml

@@ -12,9 +12,8 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - { name: '3.10-ma3', python: '3.10', tox: py310-marshmallow3 }
-          - { name: '3.10-ma4', python: '3.10', tox: py310-marshmallow4 }
-          - { name: '3.13-ma4', python: '3.13', tox: py313-marshmallow4 }
+          - { name: '3.10', python: '3.10', tox: py310 }
+          - { name: '3.13', python: '3.13', tox: py313 }
     steps:
       - uses: actions/checkout@v6
       - uses: actions/setup-python@v6

CHANGELOG.rst

@@ -1,6 +1,13 @@
 Changelog
 ---------
 
+0.48.0 (unreleased)
+*******************
+
+Other changes:
+
+- Drop support for marshmallow 3, which is EOL.
+
 0.47.0 (2026-03-22)
 *******************
 

pyproject.toml

@@ -3,7 +3,7 @@ name = "flask-smorest"
 version = "0.47.0"
 description = "Flask/Marshmallow-based REST API framework"
 readme = "README.rst"
-license = { file = "LICENSE" }
+license = "MIT"
 authors = [{ name = "Jérôme Lafréchoux", email = "jerome@jolimont.fr" }]
 maintainers = [
   { name = "Jérôme Lafréchoux", email = "jerome@jolimont.fr" },
@@ -14,7 +14,6 @@ classifiers = [
   "Topic :: Internet :: WWW/HTTP",
   "Environment :: Web Environment",
   "Framework :: Flask",
-  "License :: OSI Approved :: MIT License",
   "Programming Language :: Python :: 3 :: Only",
   "Programming Language :: Python :: 3.10",
   "Programming Language :: Python :: 3.11",
@@ -25,7 +24,7 @@ requires-python = ">=3.10"
 dependencies = [
   "werkzeug>=3.0.1,<4",
   "flask>=3.0.2,<4",
-  "marshmallow>=3.24.1,<5",
+  "marshmallow>=4.0.0,<5",
   "webargs>=8.0.0,<9",
   "apispec[marshmallow]>=6.0.0,<7",
 ]

tox.ini

@@ -1,14 +1,11 @@
 [tox]
 envlist =
     lint
-    {py310,py311,py312,py313}-marshmallow{3,4}
+    py{310,311,312,313}
 skip_missing_interpreters = True
 
 [testenv]
 extras = tests
-deps =
-    marshmallow3: marshmallow>=3.26.1,<4
-    marshmallow4: marshmallow>=4.0.0,<5
 commands =
     pytest --cov=flask_smorest --cov-branch --cov-report=term-missing --cov-report=xml