How to fix NOT_FOUND: The specified document does not exist in Firebase

// Wrong - "users" and "userId" are case-sensitive
const docRef = doc(db, "Users", userId);

// Correct - ensure exact collection and document names
const docRef = doc(db, "users", userId);
console.log(docRef.path); // Verify path in console

import { doc, getDoc } from "firebase/firestore";

const docRef = doc(db, "users", userId);
const docSnap = await getDoc(docRef);

if (docSnap.exists()) {
  console.log("Document data:", docSnap.data());
} else {
  console.log("No document found - handle gracefully");
  // Return null, show error to user, or create document
}

// First, create the parent document
await setDoc(doc(db, "users", userId), {
  email: userEmail,
  createdAt: new Date(),
});

// Then create the nested document
await setDoc(doc(db, "users", userId, "posts", postId), {
  title: "My Post",
  content: "Content here",
});

import { doc, getDocFromCache } from "firebase/firestore";

const docRef = doc(db, "users", userId);

try {
  const docSnap = await getDocFromCache(docRef);
  if (docSnap.exists()) {
    console.log("Cached document:", docSnap.data());
  }
} catch (error) {
  console.log("Document not in cache - fetch from server instead");
  const docSnap = await getDoc(docRef);
  // Handle as normal with exists() check
}

// Overly restrictive rule that might appear as NOT_FOUND
allow read: if request.auth != null;

// More explicit error message (add to your rules)
allow read: if request.auth != null else deny;

import { enableLogging } from "firebase/firestore";
enableLogging(true);

npm update firebase
# or
npm install firebase@latest

rm -rf node_modules package-lock.json
npm install