diff --git a/README.md b/README.md
index 0254a3c..664ec2a 100644
--- a/README.md
+++ b/README.md
@@ -598,14 +598,6 @@ without an `await`. Demonstrated, not assumed: a `throw` placed past the first
 and on Chrome (`pageerror`), with the rest of the run unaffected because the
 approval view had already rendered.
 
-One error is still tolerated rather than fatal, listed in `ALLOWED_ERRORS` in
-`tests/e2e/firefox/run.js` and printed on every occurrence so the concession
-stays visible in the run output: Firefox reporting an extension promise that
-settled after its page unloaded, from anywhere in the popup. Its cause was the
-site-approval popup's unawaited `sendMessage` before `window.close()`, which
-[#275](https://git.eeqj.de/sneak/AutistMask/issues/275) removed; Firefox runs
-since have not printed it, and
-[#487](https://git.eeqj.de/sneak/AutistMask/issues/487) removes the entry.
 Errors are read from the privileged `nsIConsoleService` in Marionette's chrome
 context and filtered to non-warning entries whose `sourceName` is the extension
 origin. That mechanism is not a stylistic choice. WebDriver BiDi's
diff --git a/TODO.md b/TODO.md
index 3871d10..5839216 100644
--- a/TODO.md
+++ b/TODO.md
@@ -45,6 +45,14 @@ but the review is broader than any of them.
 
 # Completed Steps
 
+- 2026-10-07: The Firefox end-to-end suite no longer tolerates any uncaught
+  extension error ([#487](https://git.eeqj.de/sneak/AutistMask/issues/487)). Its
+  one entry, Firefox reporting a popup promise that settled after the page
+  unloaded, had lost its cause with
+  [#275](https://git.eeqj.de/sneak/AutistMask/issues/275); the entry and the
+  code that printed tolerated errors are gone from `tests/e2e/firefox/run.js`,
+  and so is the README paragraph that described it.
+
 - 2026-10-07: The README's end-to-end limits now match what the two browser
   suites do to the extension
   ([#293](https://git.eeqj.de/sneak/AutistMask/issues/293)). The `window.close`
diff --git a/tests/e2e/firefox/run.js b/tests/e2e/firefox/run.js
index 67d6b3c..55679ee 100644
--- a/tests/e2e/firefox/run.js
+++ b/tests/e2e/firefox/run.js
@@ -854,37 +854,6 @@ step(
 
 // ------------------------------------------------------------- runner
 
-// Uncaught extension errors that are known, tracked and deliberately
-// tolerated, in the same spirit as ALLOWED_ERRORS in tests/e2e/harness.js:
-// every entry names the issue that will delete it, and every occurrence is
-// still printed, so tolerating one is visible in the log rather than silent.
-// This is the only concession in an otherwise zero-tolerance policy.
-const ALLOWED_ERRORS = [
-    {
-        // The site-connection buttons in src/popup/views/approval.js send
-        // their decision and call window.close() on the next line. Firefox's
-        // BaseContext.wrapPromise reports, through Cu.reportError, any
-        // extension-API promise that settles after its context unloaded —
-        // whether or not the caller attached a handler, so notify()'s catch
-        // cannot suppress it.
-        //
-        // Pre-existing, and not introduced by the promise shim: the send was
-        // already unawaited, and this suite is merely the first thing to
-        // drive that window on Firefox. It is the same teardown ordering as
-        // the issue below, whose fix — making the outcome independent of when
-        // the popup closes — removes this entry with it.
-        pattern: /Promise (?:resolved|rejected) after context unloaded/,
-        source: /\/src\/popup\/index\.js$/,
-        issue: "https://git.eeqj.de/sneak/AutistMask/issues/275",
-    },
-];
-
-function allowedFor(e) {
-    return ALLOWED_ERRORS.find(
-        (a) => a.pattern.test(e.msg) && a.source.test(e.src),
-    );
-}
-
 function formatError(e) {
     return (
         e.msg + " (" + e.src + ":" + e.line + (e.cat ? ", " + e.cat : "") + ")"
@@ -1001,20 +970,6 @@ async function main() {
                 installFailure = null;
             }
 
-            // Tolerated errors are set aside, never dropped: each one is
-            // printed with the issue that keeps it on the list, so the
-            // concession stays in the run output.
-            const tolerated = found.filter((e) => allowedFor(e));
-            found = found.filter((e) => !allowedFor(e));
-            for (const e of tolerated) {
-                console.log(
-                    "# tolerated (" +
-                        allowedFor(e).issue +
-                        "): " +
-                        formatError(e),
-                );
-            }
-
             // Any uncaught error from an extension source fails the step
             // that provoked it, whether or not its assertions passed.
             if (!failure && found.length > 0) {
@@ -1039,13 +994,7 @@ async function main() {
         // blamed on any one step, but they are still reported and they
         // still fail the run.
         await sleep(1000);
-        const trailingAll = await errors.take();
-        for (const e of trailingAll.filter((x) => allowedFor(x))) {
-            console.log(
-                "# tolerated (" + allowedFor(e).issue + "): " + formatError(e),
-            );
-        }
-        const trailing = trailingAll.filter((e) => !allowedFor(e));
+        const trailing = await errors.take();
         console.log(
             "# " +
                 (steps.length - failed) +