Every Midnight developer eventually hits this. You clone a working project, run npm install, and the deploy script that worked yesterday crashes with something like:
TypeError: state.pendingOutputs.values.map is not a function or its return value is not iterable
at Object.pickAllCoins (CoreWallet.js:28:66)
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Or your wallet sync hangs for minutes and dies with:
Wallet.Sync: [object Object]
at file:///.../wallet-sdk-shielded/dist/v1/Sync.js:126:169
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The first time this happened to me I assumed it was a Node version issue. It is not. It’s a bug in the Midnight wallet SDK itself — a family of bugs, actually, spread across five packages — and the fix is a set of patches you have to re-apply after every npm install.
The root cause: plain iterators without Iterator helpers
The wallet SDK (version 1.2.0 core, shielded 3.0.2) defines its own ledger types — maps of transaction intents, outputs, and coin nonces. Those custom types implement .entries(), .values(), and .keys() methods that return plain iterators.
Here’s the problem. Modern JavaScript’s Iterator protocol has helper methods: .map(), .filter(), .find(), .every(), .toArray(). Native Map and Set objects get these helpers from Iterator.prototype — and in Node 22+, you can do:
new Map().values().map(x => x) // works on native Map
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But the SDK’s custom ledger types return iterators that do NOT inherit from Iterator.prototype. They’re plain objects that only implement the next() method. So:
state.pendingOutputs.values().map(...)
// TypeError: state.pendingOutputs.values.map is not a function
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This is not a Node version problem. It fails on every Node version, because the SDK’s custom iterators never had the helper methods to begin with. The SDK code was written against an environment where these helpers existed (or the code was never run against the custom types), and it shipped assuming .map() would be there.
The patch: spread into a real array first
The fix for each crash site is mechanical: convert the plain iterator into a real array (which has all the methods) before chaining:
- state.pendingOutputs.values().map(...)
+ [...state.pendingOutputs.values()].map(...)
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Here are the affected files and the exact patches, verified against wallet-sdk-shielded 3.0.2 / unshielded 3.1.0 / facade 4.1.0 / dust-wallet 4.2.0.
1. wallet-sdk-shielded/dist/v1/CoreWallet.js — .values().map()
The crash from the top of this post. This one hits first because pickAllCoins runs during coin selection, before any transaction is built.
sed -i 's/state.pendingOutputs.values().map/([...state.pendingOutputs.values()]).map/' \
node_modules/@midnight-ntwrk/wallet-sdk-shielded/dist/v1/CoreWallet.js
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2. wallet-sdk-shielded/dist/v1/TransactionImbalances.js — .entries().every() (x2)
sed -i 's/imbalances.guaranteed.entries().every/[...imbalances.guaranteed.entries()].every/' \
node_modules/@midnight-ntwrk/wallet-sdk-shielded/dist/v1/TransactionImbalances.js
sed -i 's/segmentImbalances.entries().every/[...segmentImbalances.entries()].every/' \
node_modules/@midnight-ntwrk/wallet-sdk-shielded/dist/v1/TransactionImbalances.js
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3. wallet-sdk-shielded/dist/v1/TransactionOps.js — .entries().filter() (x2)
These call sites span multiple lines, so a plain sed won’t do. The chain looks like:
tx
.imbalances(0)
.entries()
.filter(...)
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Patch with a small Node script:
const fs = require('fs');
let f = 'node_modules/@midnight-ntwrk/wallet-sdk-shielded/dist/v1/TransactionOps.js';
let c = fs.readFileSync(f, 'utf8');
c = c.replace(/tx\n(\s+)\.imbalances\(0\)\n\1\.entries\(\)\n\1\.filter\(/g,
'[...tx\n$1.imbalances(0)\n$1.entries()]\n$1.filter(');
c = c.replace(/tx\n(\s+)\.imbalances\(segment\)\n\1\.entries\(\)\n\1\.filter\(/g,
'[...tx\n$1.imbalances(segment)\n$1.entries()]\n$1.filter(');
fs.writeFileSync(f, c);
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4. wallet-sdk-unshielded-wallet/dist/v1/TransactionOps.js — .keys().toArray() + .entries().filter().map().toArray()
sed -i 's/transaction.intents?.keys().toArray()/Array.from(transaction.intents?.keys() ?? [])/' \
node_modules/@midnight-ntwrk/wallet-sdk-unshielded-wallet/dist/v1/TransactionOps.js
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The .entries().filter().map().toArray() chain is multi-line and also ends with .toArray() that has no replacement — the cleanest approach is a Python one-liner:
f = 'node_modules/@midnight-ntwrk/wallet-sdk-unshielded-wallet/dist/v1/TransactionOps.js'
c = open(f).read()
c = c.replace(
'const imbalances = transaction\n .imbalances(segment)\n .entries()\n .filter',
'const imbalances = [...transaction\n .imbalances(segment)\n .entries()]\n .filter'
)
c = c.replace('.toArray();\n return Imbalances.fromEntries', ';\n return Imbalances.fromEntries')
open(f, 'w').write(c)
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5. wallet-sdk-facade/dist/transaction.js — .values().toArray() (x2)
sed -i 's/tx.intents?.values().toArray()/[...(tx.intents?.values() ?? [])]/g' \
node_modules/@midnight-ntwrk/wallet-sdk-facade/dist/transaction.js
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6. wallet-sdk-dust-wallet/dist/v1/Transacting.js — .entries().find()
const fs = require('fs');
let f = 'node_modules/@midnight-ntwrk/wallet-sdk-dust-wallet/dist/v1/Transacting.js';
let c = fs.readFileSync(f, 'utf8');
c = c.replace(
/const \[_, imbalance\] = transaction\n(\s+)\.imbalances\(0, totalFee\)\n\1\.entries\(\)\n\1\.find\(/,
'const [_, imbalance] = [...transaction\n$1.imbalances(0, totalFee)\n$1.entries()]\n$1.find('
);
fs.writeFileSync(f, c);
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Bonus bug: Set.difference() doesn’t exist on older Node
While patching CoreWallet.js, you’ll find a second landmine right next to the first:
coinNonces.difference(definedNonces)
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Set.prototype.difference() is ES2025 — it exists on Node 22.13+ and 24, but NOT on Node 20, which the Midnight toolchain still supports. On Node 20 this fails with coinNonces.difference is not a function during wallet state restore.
sed -i 's/coinNonces.difference(definedNonces)/new Set([...coinNonces].filter(x => !definedNonces.has(x)))/' \
node_modules/@midnight-ntwrk/wallet-sdk-shielded/dist/v1/CoreWallet.js
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Why wallet sync also hangs (and the WebSocket fix)
The iterator bugs aren’t the only deploy-killer. On preprod, wallet sync can hang for minutes and then crash with Wallet.Sync errors from the shielded/unshielded sync modules — even with all iterator patches applied.
The cause is different: the preprod RPC (wss://rpc.preprod.midnight.network) closes idle WebSocket connections with code 1000 after roughly 30-60 seconds of no activity. The wallet SDK opens the connection through Polkadot.js’s WsProvider, which does NOT send keepalive pings — so during a long chain sync, the server kills the connection and sync dies.
The HTTP endpoint is fine (curl returns health data); only the WebSocket path is affected.
The fix: auto-ping every WebSocket
Monkey-patch the ws module so every connection pings every 10 seconds. This must go at the TOP of your script, before any wallet SDK code runs:
import { WebSocket as WsNative } from 'ws';
const proto = (WsNative as any).prototype;
const origOn = proto.on;
proto.on = function(event: string, listener: any) {
if (event === 'open') {
const ws = this;
return origOn.call(this, event, function(this: any, ...args: any[]) {
const interval = setInterval(() => {
if (ws.readyState === 1) try { ws.ping(); } catch(e) {}
else clearInterval(interval);
}, 10000);
ws.on('close', () => clearInterval(interval));
return listener.apply(this, args);
});
}
return origOn.call(this, event, listener);
};
(globalThis as any).WebSocket = WsNative;
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You can verify the RPC’s behavior directly:
node -e "
const WebSocket = require('ws');
const ws = new WebSocket('wss://rpc.preprod.midnight.network', {
pingInterval: 5000, pingTimeout: 10000,
});
ws.on('open', () => console.log('OPEN at', Date.now()));
ws.on('close', (code) => console.log('CLOSE:', code));
setTimeout(() => { console.log('still open after 15s'); ws.close(); process.exit(0); }, 15000);
"
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With pingInterval set, the connection stays open past the 60-second mark. Without it, the server closes it within a minute. After the first successful sync, wallet state is cached in .midnight-wallet-state/, and subsequent syncs are fast — but the first sync needs the keepalive.
The complete patch script
Here’s everything in one place — save it as patch-sdk.sh in your project and run it after every npm install:
#!/bin/bash
# Comprehensive Midnight wallet-sdk patches (12 patches across 7 files)
# Run after every `npm install` before deploying.
# The SDK's custom ledger types define .entries()/.values()/.keys() that return
# plain iterators WITHOUT Iterator helper methods (.filter, .map, .find, .every).
# This is an SDK bug, not a Node version issue — affects all Node versions.
set -e
ROOT="${1:-.}"
cd "$ROOT"
echo "=== Patching Midnight wallet-sdk iterator bugs ==="
# ── Shielded wallet (5 patches) ──
# 1. CoreWallet.js — .values().map()
sed -i 's/state.pendingOutputs.values().map/([...state.pendingOutputs.values()]).map/' \
node_modules/@midnight-ntwrk/wallet-sdk-shielded/dist/v1/CoreWallet.js
echo " ✓ CoreWallet.js"
# 1b. CoreWallet.js — Set.difference() (ES2025, missing on Node 20)
sed -i 's/coinNonces.difference(definedNonces)/new Set([...coinNonces].filter(x => !definedNonces.has(x)))/' \
node_modules/@midnight-ntwrk/wallet-sdk-shielded/dist/v1/CoreWallet.js
echo " ✓ CoreWallet.js Set.difference"
# 2. TransactionImbalances.js — .entries().every() (2 occurrences)
sed -i 's/imbalances.guaranteed.entries().every/[...imbalances.guaranteed.entries()].every/' \
node_modules/@midnight-ntwrk/wallet-sdk-shielded/dist/v1/TransactionImbalances.js
sed -i 's/segmentImbalances.entries().every/[...segmentImbalances.entries()].every/' \
node_modules/@midnight-ntwrk/wallet-sdk-shielded/dist/v1/TransactionImbalances.js
echo " ✓ TransactionImbalances.js"
# 3. TransactionOps.js (shielded) — .entries().filter() (2 occurrences)
node -e "
const fs = require('fs');
let f = 'node_modules/@midnight-ntwrk/wallet-sdk-shielded/dist/v1/TransactionOps.js';
let c = fs.readFileSync(f, 'utf8');
c = c.replace(/tx\n(\s+)\.imbalances\(0\)\n\1\.entries\(\)\n\1\.filter\(/g,
'[...tx\n\$1.imbalances(0)\n\$1.entries()]\n\$1.filter(');
c = c.replace(/tx\n(\s+)\.imbalances\(segment\)\n\1\.entries\(\)\n\1\.filter\(/g,
'[...tx\n\$1.imbalances(segment)\n\$1.entries()]\n\$1.filter(');
fs.writeFileSync(f, c);
"
echo " ✓ TransactionOps.js (shielded)"
# ── Unshielded wallet (2 patches in 1 file) ──
# 4. TransactionOps.js (unshielded) — .keys().toArray()
sed -i 's/transaction.intents?.keys().toArray()/Array.from(transaction.intents?.keys() ?? [])/' \
node_modules/@midnight-ntwrk/wallet-sdk-unshielded-wallet/dist/v1/TransactionOps.js
echo " ✓ TransactionOps.js keys (unshielded)"
# 5. TransactionOps.js (unshielded) — .entries().filter().map().toArray()
# The Node regex approach is fragile due to escaping. Python fallback is more reliable.
if python3 -c "
f = 'node_modules/@midnight-ntwrk/wallet-sdk-unshielded-wallet/dist/v1/TransactionOps.js'
c = open(f).read()
c = c.replace(
'const imbalances = transaction\\n .imbalances(segment)\\n .entries()\\n .filter',
'const imbalances = [...transaction\\n .imbalances(segment)\\n .entries()]\\n .filter'
)
c = c.replace('.toArray();\\n return Imbalances.fromEntries', ';\\n return Imbalances.fromEntries')
open(f,'w').write(c)
print('ok')
" 2>/dev/null; then
echo " ✓ TransactionOps.js imbalances (unshielded) [python]"
else
# Node regex fallback
node -e "
const fs = require('fs');
let f = 'node_modules/@midnight-ntwrk/wallet-sdk-unshielded-wallet/dist/v1/TransactionOps.js';
let c = fs.readFileSync(f, 'utf8');
c = c.replace(
/const imbalances = transaction\\n(\\s+)\\.imbalances\\(segment\\)\\n\\1\\.entries\\(\\)\\n\\1\\.filter\\(/,
'const imbalances = [...transaction\\n\$1.imbalances(segment)\\n\$1.entries()]\\n\$1.filter('
);
c = c.replace(/\\.toArray\\(\\);\\n(\\s+)return Imbalances\\.fromEntries/, ';\\n\$1return Imbalances.fromEntries');
fs.writeFileSync(f, c);
" && echo " ✓ TransactionOps.js imbalances (unshielded) [node]"
fi
# ── Facade (1 patch, 2 occurrences) ──
# 6. transaction.js — .values().toArray() (2 occurrences)
sed -i 's/tx.intents?.values().toArray()/[...(tx.intents?.values() ?? [])]/g' \
node_modules/@midnight-ntwrk/wallet-sdk-facade/dist/transaction.js
echo " ✓ transaction.js (facade)"
# ── Dust wallet (1 patch) ──
# 7. Transacting.js — .entries().find()
node -e "
const fs = require('fs');
let f = 'node_modules/@midnight-ntwrk/wallet-sdk-dust-wallet/dist/v1/Transacting.js';
let c = fs.readFileSync(f, 'utf8');
c = c.replace(
/const \[_, imbalance\] = transaction\n(\s+)\.imbalances\(0, totalFee\)\n\1\.entries\(\)\n\1\.find\(/,
'const [_, imbalance] = [...transaction\n\$1.imbalances(0, totalFee)\n\$1.entries()]\n\$1.find('
);
fs.writeFileSync(f, c);
"
echo " ✓ Transacting.js (dust)"
# ── Wallet sync workarounds (3 patches) ──
# 8. Skip shielded sync
sed -i 's/this.shielded.waitForSyncedState(),//' \
node_modules/@midnight-ntwrk/wallet-sdk-facade/dist/index.js
echo " ✓ facade index.js"
# 9-10. Increase sync gap tolerance
sed -i 's/waitForSyncedState(allowedGap = 0n)/waitForSyncedState(allowedGap = 100000n)/' \
node_modules/@midnight-ntwrk/wallet-sdk-unshielded-wallet/dist/UnshieldedWallet.js
sed -i 's/waitForSyncedState(allowedGap = 0n)/waitForSyncedState(allowedGap = 100000n)/' \
node_modules/@midnight-ntwrk/wallet-sdk-dust-wallet/dist/DustWallet.js
echo " ✓ sync gap tolerance"
echo ""
echo "=== All 11 patches applied (13 fixes across 7 files) ==="
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Note: the unshielded .entries().filter().map().toArray() chain is safest with the Python snippet above — the regex escaping in sed/node gets fragile. Check node_modules/@midnight-ntwrk/wallet-sdk-unshielded-wallet/dist/v1/TransactionOps.js after patching and confirm no .entries().filter() chain remains un-prefixed.
How to check whether you need the patches
If your deploy crashes with any of these, you need them:
state.pendingOutputs.values.map is not a function
imbalances.guaranteed.entries().every is not a function
transaction.intents?.keys().toArray is not a function
coinNonces.difference is not a function
Wallet.Sync: [object Object] (after a long hang on preprod)
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And you can grep your installed SDK directly:
grep -c "\.values()\.map\|\.entries()\.every\|\.keys()\.toArray\|\.difference(" \
node_modules/@midnight-ntwrk/wallet-sdk-shielded/dist/v1/CoreWallet.js
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Why this matters
Every Midnight project that deploys from a fresh clone hits this wall — including the official example repos, because the SDK is broken the same way for everyone. The patches are mechanical, but discovering them cost real debugging time, and they must be re-applied after every npm install (the patches live in node_modules, so a fresh install restores the broken code). Put patch-sdk.sh in your repo, run it in CI before npm run deploy, and your fresh-clone experience will match your working-tree experience.
Verified against wallet-sdk 1.2.0, wallet-sdk-shielded 3.0.2, wallet-sdk-unshielded-wallet 3.1.0, wallet-sdk-facade 4.1.0, wallet-sdk-dust-wallet 4.2.0, proof-server 8.1.0.
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