diff --git a/CHANGES b/CHANGES
index 5b890fe8420..3739db03572 100644
--- a/CHANGES
+++ b/CHANGES
@@ -13,6 +13,9 @@ Deprecated
 Features added
 --------------
 
+* Revert the removal of ``sphinx.util:force_decode()`` to become some 3rd party
+  extensions available again during 5.0
+
 Bugs fixed
 ----------
 
diff --git a/doc/extdev/deprecated.rst b/doc/extdev/deprecated.rst
index 9e17b9fb4f0..e37c2b2ba4b 100644
--- a/doc/extdev/deprecated.rst
+++ b/doc/extdev/deprecated.rst
@@ -1015,7 +1015,7 @@ The following is a list of deprecated interfaces.
 
    * - ``sphinx.util.force_decode()``
      - 2.0
-     - 4.0
+     - 5.0
      - N/A
 
    * - ``sphinx.util.get_matching_docs()``
diff --git a/sphinx/util/__init__.py b/sphinx/util/__init__.py
index 7e24909ee83..170c554d77b 100644
--- a/sphinx/util/__init__.py
+++ b/sphinx/util/__init__.py
@@ -337,6 +337,23 @@ def parselinenos(spec: str, total: int) -> List[int]:
     return items
 
 
+def force_decode(string: str, encoding: str) -> str:
+    """Forcibly get a unicode string out of a bytestring."""
+    warnings.warn('force_decode() is deprecated.',
+                  RemovedInSphinx50Warning, stacklevel=2)
+    if isinstance(string, bytes):
+        try:
+            if encoding:
+                string = string.decode(encoding)
+            else:
+                # try decoding with utf-8, should only work for real UTF-8
+                string = string.decode()
+        except UnicodeError:
+            # last resort -- can't fail
+            string = string.decode('latin1')
+    return string
+
+
 def rpartition(s: str, t: str) -> Tuple[str, str]:
     """Similar to str.rpartition from 2.5, but doesn't return the separator."""
     warnings.warn('rpartition() is now deprecated.', RemovedInSphinx50Warning, stacklevel=2)