Lost 6 hours upgrading Flutter. Documented every error so you don't have to.

Background: I am the solo developer behind DramaHub — a production OTT streaming app on Android, 7,500+ downloads, 2,500+ daily active users, running at ₹0/month infrastructure cost using GitHub as the database and Cloudflare Workers as the CDN.

Yesterday I upgraded Flutter from 3.29 to 3.41.9 because my ad monetization SDK (CAS) required it.

Six hours later, after four separate cascading errors, the build finally worked.
I documented every error, every root cause, and every fix in a Dev.to article: https://dev.to/waseyjamal/i-upgraded-flutter-and-lost-6-hours-heres-the-fix-that-takes-10-minutes-3pe0

Quick summary of what went wrong:
Error 1 — settings.gradle.kts was missing the pluginManagement block entirely (broke Gradle plugin resolution)

Error 2 — Flutter SDK was installed at C:\flutter owned by Administrator instead of user folder (broke Git ownership checks)

Error 3 — build.gradle.kts was missing Flutter's build directory redirect block (APK built successfully but Flutter couldn't find it)

Error 4 — JVM heap too low for large ad SDK collection (OutOfMemoryError during DEX merging)
The third error was the brutal one. BUILD SUCCESSFUL in the terminal. "Failed to produce APK" from Flutter. The APK existed — it was just in the wrong folder because of one missing block in one config file.

If you run a Flutter Android app with ads or plan to upgrade Flutter on Windows, the article covers everything.
Happy to answer questions here too.