diff --git a/CHANGELOG.md b/CHANGELOG.md
index cf5ebd5fd..306b38426 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - Remove deprecation warnings by using `Module#registerHooks` instead of `Module#register` on Node 26+ ([#20028](https://github.com/tailwindlabs/tailwindcss/pull/20028))
+- Canonicalization: don't crash when plugin utilities throw for unsupported values ([#20052](https://github.com/tailwindlabs/tailwindcss/pull/20052))
 
 ## [4.3.0] - 2026-05-08
 
diff --git a/packages/tailwindcss/src/canonicalize-candidates.test.ts b/packages/tailwindcss/src/canonicalize-candidates.test.ts
index 4bf446a26..81a53929f 100644
--- a/packages/tailwindcss/src/canonicalize-candidates.test.ts
+++ b/packages/tailwindcss/src/canonicalize-candidates.test.ts
@@ -5,6 +5,7 @@ import { describe, expect, test } from 'vitest'
 import { __unstable__loadDesignSystem } from '.'
 import { cartesian } from './cartesian'
 import type { CanonicalizeOptions } from './intellisense'
+import plugin from './plugin'
 import { DefaultMap } from './utils/default-map'
 
 const css = String.raw
@@ -1419,4 +1420,51 @@ describe('regressions', () => {
       expect(designSystem.canonicalizeCandidates(candidates, options)).toEqual(expected)
     },
   )
+
+  // https://github.com/tailwindlabs/tailwindcss/issues/20051
+  test(
+    'does not crash when plugin matchComponents rejects speculative values during collapse',
+    { timeout },
+    async () => {
+      let designSystem = await __unstable__loadDesignSystem(
+        css`
+          @import 'tailwindcss';
+          @plugin "./plugin.js";
+        `,
+        {
+          async loadStylesheet(_, base) {
+            return {
+              base,
+              path: '',
+              content: '@tailwind utilities;',
+            }
+          },
+          async loadModule() {
+            return {
+              base: '',
+              path: '',
+              module: plugin(({ matchComponents }) => {
+                matchComponents(
+                  {
+                    myicon: () => {
+                      throw new Error('Mimic as-if a custom plugin failed for some reason')
+                    },
+                  },
+                  { values: { icon: __filename } },
+                )
+              }),
+            }
+          },
+        },
+      )
+
+      expect(
+        designSystem.canonicalizeCandidates(['border-[1.5px]', 'flex'], {
+          collapse: true,
+          logicalToPhysical: true,
+          rem: 16,
+        }),
+      ).toEqual(expect.arrayContaining(['border-[1.5px]', 'flex']))
+    },
+  )
 })
diff --git a/packages/tailwindcss/src/canonicalize-candidates.ts b/packages/tailwindcss/src/canonicalize-candidates.ts
index 118f51e60..9a0b0e6af 100644
--- a/packages/tailwindcss/src/canonicalize-candidates.ts
+++ b/packages/tailwindcss/src/canonicalize-candidates.ts
@@ -2614,13 +2614,9 @@ function createUtilityPropertiesCache(
       let parsed = designSystem.parseCandidate(className)
       if (parsed.length === 0) return localPropertyValueLookup
 
-      walk(
-        canonicalizeAst(
-          designSystem,
-          designSystem.compileAstNodes(parsed[0]).map((x) => cloneAstNode(x.node)),
-          options,
-        ),
-        (node) => {
+      try {
+        let ast = designSystem.compileAstNodes(parsed[0]).map((x) => cloneAstNode(x.node))
+        walk(canonicalizeAst(designSystem, ast, options), (node) => {
           if (node.kind === 'declaration') {
             localPropertyValueLookup.get(node.property).add(node.value!)
             designSystem.storage[STATIC_UTILITIES_KEY].get(options)
@@ -2628,8 +2624,12 @@ function createUtilityPropertiesCache(
               .get(node.value!)
               .add(className)
           }
-        },
-      )
+        })
+      } catch {
+        // Ignore errors, this could happen when we call a plugin with a value
+        // it didn't expect. But since plugins are functions, we can't know
+        // ahead of time what it expects.
+      }
 
       return localPropertyValueLookup
     })