Firestore Error After Upgrading to Firebase JS SDK v12.6.0 — “Change version backslides” #9414
Description
Operating System
Windows 11, MacOS
Environment
Framework: Angular 21, Node.js version: 20.11.1, Package Manager: npm 10.2+, Browser versions observed: Chrome 131, Safari 18, Firefox 132
Firebase SDK Version
12.6.0
Firebase SDK Product(s)
Firestore
Project Tooling
• Framework: Angular 21 (standalone components, zoneless change detection)
• Build System: Angular CLI using esbuild for bundling
• TypeScript: v5.5+
• Package Manager: npm (v10.x)
• Node.js: v20.11.1
⸻
Detailed Problem Description
We recently upgraded our application from Firebase JS SDK 12.5.0 → 12.6.0. After the upgrade, we began seeing new intermittent Firestore errors in production that never occurred before. Our goal was simply to stay up-to-date with the latest SDK release—no Firestore logic, listeners, or backend behavior changed on our side.
What we were trying to achieve
• Maintain current Firebase versions.
• Continue using Firestore snapshot listeners as usual.
• No functional changes were made to our Firestore implementation.
What actually happened
Immediately after upgrading to v12.6.0, we started receiving intermittent Firestore internal errors in production. These errors appear to be thrown during Firestore’s streaming / watch pipeline (snapshot listeners).
The application continues functioning, but logs indicate unexpected internal state inconsistencies within Firestore.
Reverting to v12.5.0 makes the issue disappear completely.
Unexpected behavior / Error message
Example error:
Change version backslides. StreamingTargetHandle: 6
Current version: 1765101794777310
Change version: 1765101794776157
Example stack trace:
s@https://www.acro-companion.com/chunk-5DLN5Q7L.js:48:1720
ht@https://www.acro-companion.com/chunk-5DLN5Q7L.js:58:11910
0@https://www.acro-companion.com/chunk-5DLN5Q7L.js:61:12110
Ste@https://www.acro-companion.com/chunk-5DLN5Q7L.js:61:12129
onNext@https://www.acro-companion.com/chunk-5DLN5Q7L.js:66:36719
0@https://www.acro-companion.com/chunk-5DLN5Q7L.js:70:35472
0@https://www.acro-companion.com/chunk-5DLN5Q7L.js:70:35888
This repeats with different StreamingTargetHandle values, but the same pattern.
Additional Notes
• These errors began exactly after upgrading to v12.6.0.
• They do not appear in v12.5.0 or earlier.
• No application behavior changed around Firestore logic during the upgrade.
• Errors occur in production under normal usage patterns with multiple active snapshot listeners.
Steps and code to reproduce issue
Since the issue is intermittent, no deterministic reproduction steps yet.
Error appears during:
• Firestore listeners
• Possibly internal state updates