diff --git a/packages/SwingSet/misc-tools/extract-xs-snapshot.js b/packages/SwingSet/misc-tools/extract-xs-snapshot.js
index 75fde2527620..0fd5da580424 100644
--- a/packages/SwingSet/misc-tools/extract-xs-snapshot.js
+++ b/packages/SwingSet/misc-tools/extract-xs-snapshot.js
@@ -55,7 +55,7 @@ if (!vatIDToExtract) {
   const { snapPos, hash } = info;
   const snapshot = snapStore.loadSnapshot(vatIDToExtract);
   const fn = `${vatIDToExtract}-${snapPos}-${hash}.xss`;
-  E.when(fs.promises.writeFile(fn, snapshot), () =>
+  void E.when(fs.promises.writeFile(fn, snapshot), () =>
     console.log(`wrote snapshot to ${fn}`),
   );
 }
diff --git a/packages/SwingSet/test/test-vat-timer.js b/packages/SwingSet/test/test-vat-timer.js
index d5d6d2f37f1a..ef1a5b305add 100644
--- a/packages/SwingSet/test/test-vat-timer.js
+++ b/packages/SwingSet/test/test-vat-timer.js
@@ -269,8 +269,8 @@ test('brand', async t => {
   const whenNobrand = 123n;
   const delayNobrand = 123n;
   ts.setWakeup(whenNobrand, handler);
-  ts.wakeAt(whenNobrand);
-  ts.delay(delayNobrand);
+  void ts.wakeAt(whenNobrand);
+  void ts.delay(delayNobrand);
   ts.makeRepeater(delayNobrand, delayNobrand);
   ts.repeatAfter(delayNobrand, delayNobrand, handler);
   ts.makeNotifier(delayNobrand, delayNobrand);
diff --git a/packages/SwingSet/test/transcript/test-state-sync-reload.js b/packages/SwingSet/test/transcript/test-state-sync-reload.js
index 1eb72d925804..7174c5cd54bf 100644
--- a/packages/SwingSet/test/transcript/test-state-sync-reload.js
+++ b/packages/SwingSet/test/transcript/test-state-sync-reload.js
@@ -59,7 +59,7 @@ test('state-sync reload', async t => {
   const { commit } = hostStorage;
   const initOpts = { addComms: false, addVattp: false, addTimer: false };
   await initializeSwingset(config, [], kernelStorage, initOpts);
-  commit();
+  void commit();
 
   const { runtimeOptions } = t.context.data;
   const c1 = await makeSwingsetController(kernelStorage, {}, runtimeOptions);
@@ -82,7 +82,7 @@ test('state-sync reload', async t => {
     t.is(res, i);
   }
 
-  commit();
+  void commit();
   await c1.shutdown();
 
   const exporter = makeSwingStoreExporter(dbDir);
diff --git a/packages/SwingSet/test/transcript/test-transcript-entries.js b/packages/SwingSet/test/transcript/test-transcript-entries.js
index 636b9a16353d..dd2aecb63c9c 100644
--- a/packages/SwingSet/test/transcript/test-transcript-entries.js
+++ b/packages/SwingSet/test/transcript/test-transcript-entries.js
@@ -117,12 +117,12 @@ test('transcript spans', async t => {
   const { commit } = hostStorage;
   const initOpts = { addComms: false, addVattp: false, addTimer: false };
   await initializeSwingset(config, [], kernelStorage, initOpts);
-  commit();
+  void commit();
 
   let c;
   const restart = async () => {
     if (c) {
-      commit();
+      void commit();
       await c.shutdown();
     }
     const { runtimeOptions } = t.context.data;
diff --git a/packages/cosmic-swingset/scripts/clean-core-eval.js b/packages/cosmic-swingset/scripts/clean-core-eval.js
index 5cd036e3cf3c..b982b66415f9 100755
--- a/packages/cosmic-swingset/scripts/clean-core-eval.js
+++ b/packages/cosmic-swingset/scripts/clean-core-eval.js
@@ -62,7 +62,7 @@ export const main = async (argv, { readFile, stdout }) => {
 
 if (isEntrypoint(import.meta.url)) {
   /* global process */
-  farExports.E.when(
+  void farExports.E.when(
     import('fs/promises'),
     fsp =>
       main([...process.argv], {
diff --git a/packages/internal/src/queue.js b/packages/internal/src/queue.js
index fbff279c8900..6f9e8e2d0ed8 100644
--- a/packages/internal/src/queue.js
+++ b/packages/internal/src/queue.js
@@ -17,7 +17,7 @@ export const makeWithQueue = () => {
     }
     const [thunk, resolve, reject] = queue[0];
     // Run the thunk in a new turn.
-    Promise.resolve()
+    void Promise.resolve()
       .then(thunk)
       // Resolve or reject our caller with the thunk's value.
       .then(resolve, reject)
diff --git a/packages/solo/public/main.js b/packages/solo/public/main.js
index 291740ffb3b6..8306003dfb2d 100644
--- a/packages/solo/public/main.js
+++ b/packages/solo/public/main.js
@@ -266,7 +266,7 @@ function run() {
     commands[commands.length - 1] = inp.value;
     commands[commands.length] = '';
     inp.value = '';
-    call({ type: 'doEval', number, body: command });
+    void call({ type: 'doEval', number, body: command });
   }
 
   function inputKeyup(ev) {
diff --git a/packages/solo/src/captp.js b/packages/solo/src/captp.js
index d949a327331f..2052d954553e 100644
--- a/packages/solo/src/captp.js
+++ b/packages/solo/src/captp.js
@@ -43,7 +43,9 @@ export const getCapTPHandler = (send, getLocalBootstrap, fallback) => {
         dispatch,
         abort,
       });
-      doFallback('onOpen', obj, meta);
+      doFallback('onOpen', obj, meta).catch(e => {
+        console.error(`Error in fallback onOpen`, e);
+      });
     },
     onClose(obj, meta) {
       console.debug(`Finishing CapTP`, meta);
@@ -53,7 +55,9 @@ export const getCapTPHandler = (send, getLocalBootstrap, fallback) => {
         abort();
       }
       chans.delete(meta.channelHandle);
-      doFallback('onClose', obj, meta);
+      doFallback('onClose', obj, meta).catch(e => {
+        console.error(`Error in fallback onClose`, e);
+      });
     },
     onError(obj, meta) {
       console.debug(`Error in CapTP`, meta, obj.error);
@@ -62,7 +66,9 @@ export const getCapTPHandler = (send, getLocalBootstrap, fallback) => {
         const { abort } = chan;
         abort(obj.error);
       }
-      doFallback('onError', obj, meta);
+      doFallback('onError', obj, meta).catch(e => {
+        console.error(`Error in fallback onError`, e);
+      });
     },
     async onMessage(obj, meta) {
       console.debug('processing inbound', obj);
diff --git a/packages/solo/src/chain-cosmos-sdk.js b/packages/solo/src/chain-cosmos-sdk.js
index c6b287aa3609..c4f4c3342bee 100644
--- a/packages/solo/src/chain-cosmos-sdk.js
+++ b/packages/solo/src/chain-cosmos-sdk.js
@@ -258,7 +258,7 @@ export async function connectToChain(
    */
   const getMailboxNotifier = () => {
     const { notifier, updater } = makeNotifierKit();
-    retryRpcHref(async rpcHref => {
+    void retryRpcHref(async rpcHref => {
       // Every time we enter this function, we are establishing a
       // new websocket to a potentially different RPC server.
       //
@@ -486,7 +486,7 @@ export async function connectToChain(
 
         waitForTxHash = subscribeAndWaitForTxHash;
         if (postponedTxHash) {
-          subscribeAndWaitForTxHash(postponedTxHash);
+          void subscribeAndWaitForTxHash(postponedTxHash);
         }
 
         subscribeToStorage(`mailbox.${clientAddr}`, (err, storageValue) => {
@@ -692,15 +692,20 @@ ${chainID} chain does not yet know of address ${clientAddr}${adviseEgress(
           // Wait for the transaction to be included in a block.
           const txHash = out.txhash;
 
-          waitForTxHash(txHash).then(txResult => {
-            // The result had an error code (not 0 or undefined for success).
-            if (txResult.code) {
+          waitForTxHash(txHash)
+            .then(txResult => {
+              // The result had an error code (not 0 or undefined for success).
+              if (txResult.code) {
+                // eslint-disable-next-line no-use-before-define
+                failedSend(
+                  assert.error(`Error in tx processing: ${txResult.log}`),
+                );
+              }
+            })
+            .catch(err =>
               // eslint-disable-next-line no-use-before-define
-              failedSend(
-                assert.error(`Error in tx processing: ${txResult.log}`),
-              );
-            }
-          });
+              failedSend(assert.error(`Error in tx processing: ${err}`)),
+            );
 
           // We submitted the transaction to the mempool successfully.
           // Preemptively increment our sequence number to avoid needing to
@@ -778,7 +783,7 @@ ${chainID} chain does not yet know of address ${clientAddr}${adviseEgress(
     updateCount || Fail`Sending unexpectedly finished!`;
 
     await sendFromMessagePool().then(successfulSend, failedSend);
-    recurseEachSend(updateCount);
+    void recurseEachSend(updateCount);
   };
 
   // Begin the sender when we get the first (empty) mailbox update.
diff --git a/packages/solo/src/vat-http.js b/packages/solo/src/vat-http.js
index 58fb4d29fa42..70e638e6ff3d 100644
--- a/packages/solo/src/vat-http.js
+++ b/packages/solo/src/vat-http.js
@@ -108,7 +108,7 @@ export function buildRootObject(vatPowers) {
       commandDevice = d;
 
       const replHandler = getReplHandler(replObjects, send);
-      registerURLHandler(replHandler, '/private/repl');
+      void registerURLHandler(replHandler, '/private/repl');
 
       // Assign the captp handler.
       const captpHandler = Far('captpHandler', {
@@ -127,7 +127,7 @@ export function buildRootObject(vatPowers) {
           return harden(exported);
         },
       });
-      registerURLHandler(captpHandler, '/private/captp');
+      void registerURLHandler(captpHandler, '/private/captp');
     },
 
     registerURLHandler,
diff --git a/packages/solo/test/captp-fixture.js b/packages/solo/test/captp-fixture.js
index 999d87081b49..38632f9fd90f 100644
--- a/packages/solo/test/captp-fixture.js
+++ b/packages/solo/test/captp-fixture.js
@@ -109,7 +109,7 @@ export async function makeFixture(PORT, noisy = false) {
         // We only reject if the child exits before CapTP is established.
         reject(Error(`CapTP fixture exited with ${code}`));
       });
-      tryConnect(resolve, reject);
+      void tryConnect(resolve, reject);
     });
   }
 
diff --git a/packages/swingset-liveslots/src/liveslots.js b/packages/swingset-liveslots/src/liveslots.js
index a6d6a7fe849c..63ea6dd0d50e 100644
--- a/packages/swingset-liveslots/src/liveslots.js
+++ b/packages/swingset-liveslots/src/liveslots.js
@@ -1602,7 +1602,7 @@ function build(
       // *not* directly wait for the userspace function to complete, nor for
       // any promise it returns to fire.
       const p = Promise.resolve(delivery).then(unmeteredDispatch);
-      p.finally(() => (complete = true));
+      void p.finally(() => (complete = true));
 
       // Instead, we wait for userspace to become idle by draining the
       // promise queue. We clean up and then examine/return 'p' so any
diff --git a/packages/xsnap/src/xsnap.js b/packages/xsnap/src/xsnap.js
index 5d605d581f2f..804b90efbb4d 100644
--- a/packages/xsnap/src/xsnap.js
+++ b/packages/xsnap/src/xsnap.js
@@ -152,7 +152,7 @@ export async function xsnap(options) {
       sourceStream.pipe(destStream, { end: false });
 
       done = finished(sourceStream);
-      done.catch(noop).then(() => sourceStream.unpipe(destStream));
+      done.catch(noop).then(() => sourceStream.unpipe(destStream), noop);
     };
 
     return harden({
@@ -264,7 +264,7 @@ export async function xsnap(options) {
         loadSnapshotHandler = undefined;
         return cleanup();
       }
-    });
+    }, noop);
   }
 
   /** @type {Promise<void>} */
@@ -458,10 +458,10 @@ export async function xsnap(options) {
         const handle = await fs.open(snapPath, 'w+');
         // @ts-expect-error 'close' event added in Node 15.4
         handle.on('close', () => {
-          fs.unlink(snapPath);
+          void fs.unlink(snapPath);
         });
         sourceStream = handle.createReadStream();
-        finished(output).finally(() => sourceStream.destroy());
+        void finished(output).finally(() => sourceStream.destroy());
       } else {
         sourceStream = snapshotSaveStream;
         snapPath = `@${SNAPSHOT_SAVE_FD}`;
@@ -470,7 +470,7 @@ export async function xsnap(options) {
         // ensuring that any previous save stream usage has ended. However we
         // must start the flow before receiving the command's response or the
         // xsnap process would block on a full pipe, causing an IPC deadlock.
-        batonKit.promise.then(maybePipe);
+        batonKit.promise.then(maybePipe, noop);
       }
 
       const cleanup = () => {
diff --git a/packages/xsnap/src/xsrepl.js b/packages/xsnap/src/xsrepl.js
index 0f2e5b6f7b7a..c5c5f6cfb584 100755
--- a/packages/xsnap/src/xsrepl.js
+++ b/packages/xsnap/src/xsrepl.js
@@ -97,4 +97,4 @@ async function main() {
   return vat.close();
 }
 
-main();
+await main();
diff --git a/packages/xsnap/test/fixture-xsnap-script.js b/packages/xsnap/test/fixture-xsnap-script.js
index 170883f397e2..d2c06c4e9357 100644
--- a/packages/xsnap/test/fixture-xsnap-script.js
+++ b/packages/xsnap/test/fixture-xsnap-script.js
@@ -1,5 +1,5 @@
 /* eslint @typescript-eslint/no-floating-promises: "warn" */
 /* global issueCommand */
-(async () => {
+void (async () => {
   issueCommand(new TextEncoder().encode('Hello, World!').buffer);
 })();