diff --git a/ChangeLog.md b/ChangeLog.md
index ccea0188db51a..d7be2223178e6 100644
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -20,6 +20,9 @@ See docs/process.md for more on how version tagging works.
 
 4.0.17 (in development)
 -----------------------
+- Minimum Firefox version was bumped up to Firefox 68 ESR, since older Firefox
+  versions are not able to run the parallel browser harness: (#25493)
+  - Firefox: v65 -> v68
 
 4.0.16 - 10/07/25
 -----------------
diff --git a/site/source/docs/tools_reference/settings_reference.rst b/site/source/docs/tools_reference/settings_reference.rst
index a01aafb6c5c66..e5a45fdedb64d 100644
--- a/site/source/docs/tools_reference/settings_reference.rst
+++ b/site/source/docs/tools_reference/settings_reference.rst
@@ -2871,7 +2871,7 @@ are desired to work. Pass -sMIN_FIREFOX_VERSION=majorVersion to drop support
 for Firefox versions older than < majorVersion.
 Firefox 79 was released on 2020-07-28.
 MAX_INT (0x7FFFFFFF, or -1) specifies that target is not supported.
-Minimum supported value is 65 which was released on 2019-01-29 (see
+Minimum supported value is 68 which was released on 2019-07-09 (see
 feature_matrix.py)
 
 Default value: 79
diff --git a/src/lib/libwebgl.js b/src/lib/libwebgl.js
index e06cd745fd2ba..4e4cc09d72eba 100644
--- a/src/lib/libwebgl.js
+++ b/src/lib/libwebgl.js
@@ -859,17 +859,6 @@ for (/**@suppress{duplicate}*/var i = 0; i <= {{{ GL_POOL_TEMP_BUFFERS_SIZE }}};
       if (gl.getContextAttributes().antialias) {
         context.defaultFboForbidBlitFramebuffer = true;
       }
-#if MIN_FIREFOX_VERSION < 67
-      else {
-        // The WebGL 2 blit path doesn't work in Firefox < 67 (except in fullscreen).
-        // https://bugzil.la/1523030
-        var firefoxMatch = navigator.userAgent.toLowerCase().match(/firefox\/(\d\d)/);
-        if (firefoxMatch != null) {
-          var firefoxVersion = firefoxMatch[1];
-          context.defaultFboForbidBlitFramebuffer = firefoxVersion < 67;
-        }
-      }
-#endif
 #endif
 
       // Create render targets to the FBO
diff --git a/src/settings.js b/src/settings.js
index 6a9cdc883316d..85353517d518e 100644
--- a/src/settings.js
+++ b/src/settings.js
@@ -1880,7 +1880,7 @@ var AUTO_NATIVE_LIBRARIES = true;
 // for Firefox versions older than < majorVersion.
 // Firefox 79 was released on 2020-07-28.
 // MAX_INT (0x7FFFFFFF, or -1) specifies that target is not supported.
-// Minimum supported value is 65 which was released on 2019-01-29 (see
+// Minimum supported value is 68 which was released on 2019-07-09 (see
 // feature_matrix.py)
 // [link]
 var MIN_FIREFOX_VERSION = 79;
diff --git a/test/common.py b/test/common.py
index d5f6b70456d26..b16d2cceeef0a 100644
--- a/test/common.py
+++ b/test/common.py
@@ -116,9 +116,6 @@ def configure(data_dir):
     """Chrome has no special configuration step."""
 
 
-# N.b. The earliest Firefox version that can run multithreaded browser harness
-# is Firefox 67. If you need to test earlier Firefox versions, use EMTEST_CORES=1
-# environment variable to revert to the single-threaded browser harness.
 class FirefoxConfig:
   data_dir_flag = '-profile '
   default_flags = ('-new-instance',)
diff --git a/test/test_other.py b/test/test_other.py
index 8caf035a2f2b6..884b610d0a0a8 100644
--- a/test/test_other.py
+++ b/test/test_other.py
@@ -10530,7 +10530,7 @@ def compile(flags):
     compile(['-sMIN_SAFARI_VERSION=160000', '-mno-sign-ext'])
     verify_features_sec_linked('sign-ext', False)
     # Flag enabling overrides explicit browser version
-    compile(['-sMIN_FIREFOX_VERSION=65', '-msign-ext'])
+    compile(['-sMIN_FIREFOX_VERSION=68', '-msign-ext'])
     verify_features_sec_linked('sign-ext', True)
     # Flag disabling overrides explicit version for bulk memory
     compile(['-sMIN_SAFARI_VERSION=150000', '-mno-bulk-memory'])
@@ -14382,8 +14382,8 @@ def test_min_browser_version(self):
     err = self.expect_fail([EMCC, test_file('hello_world.c'), '-Wno-transpile', '-Werror', '-sWASM_BIGINT', '-sMIN_SAFARI_VERSION=130000'])
     self.assertContained('emcc: error: MIN_SAFARI_VERSION=130000 is not compatible with WASM_BIGINT (MIN_SAFARI_VERSION=150000 or above required)', err)
 
-    err = self.expect_fail([EMCC, test_file('hello_world.c'), '-Wno-transpile', '-Werror', '-pthread', '-sMIN_FIREFOX_VERSION=65'])
-    self.assertContained('emcc: error: MIN_FIREFOX_VERSION=65 is not compatible with pthreads (MIN_FIREFOX_VERSION=79 or above required)', err)
+    err = self.expect_fail([EMCC, test_file('hello_world.c'), '-Wno-transpile', '-Werror', '-pthread', '-sMIN_FIREFOX_VERSION=68'])
+    self.assertContained('emcc: error: MIN_FIREFOX_VERSION=68 is not compatible with pthreads (MIN_FIREFOX_VERSION=79 or above required)', err)
 
   # Test that using two different ways to disable a target environment at the same time will not produce a warning.
   def test_double_disable_environment(self):
diff --git a/tools/feature_matrix.py b/tools/feature_matrix.py
index 55e2d701438b4..c953922b8f5c9 100644
--- a/tools/feature_matrix.py
+++ b/tools/feature_matrix.py
@@ -23,7 +23,7 @@
 # N.b. when modifying these values, update comments in src/settings.js on
 # MIN_x_VERSION fields to match accordingly.
 OLDEST_SUPPORTED_CHROME = 74  # Released on 2019-04-23
-OLDEST_SUPPORTED_FIREFOX = 65  # Released on 2019-01-29
+OLDEST_SUPPORTED_FIREFOX = 68  # Released on 2019-07-09
 OLDEST_SUPPORTED_SAFARI = 120200  # Released on 2019-03-25
 # 12.22.09 is the oldest version of node that we do any testing with.
 # Keep this in sync with the test-node-compat in .circleci/config.yml.