sGTM Preview/Debug Not Working Reliably on Android While iOS Works with Identical Configuration

[dilippatil91]

Describe your environment

Flutter firebase_analytics (Dart) | 12.4.1
Flutter firebase_core (Dart) | 4.9.0
Android firebase-analytics (resolved) | 23.2.0
Android play-services-measurement (resolved) | 23.2.0
Android play-services-tagmanager | 18.3.0 (latest)
Firebase BOM (declared) | 33.12.0
Google Services Plugin | 4.4.2
Android compileSdk / targetSdk / minSdk | 36 / 36 / 26
Google Play Services Dynamite Module | measurementdynamite@262532029@26.25.32
Test Device | Samsung SM-S908E, Android 14

AndroidManifest.xml:

<meta-data
    android:name="google_analytics_default_allow_analytics_storage"
    android:value="true" />

<meta-data
    android:name="google_analytics_default_allow_ad_storage"
    android:value="false" />

<meta-data
    android:name="google_analytics_default_allow_ad_user_data"
    android:value="false" />

<meta-data
    android:name="google_analytics_default_allow_ad_personalization_signals"
    android:value="false" />

<meta-data
    android:name="google_analytics_sgtm_upload_enabled"
    android:value="true" />

<activity
    android:name="com.google.firebase.analytics.GoogleAnalyticsServerPreviewActivity"
    android:exported="true"
    android:noHistory="true">

    <intent-filter>
        <action android:name="android.intent.action.VIEW" />
        <category android:name="android.intent.category.DEFAULT" />
        <category android:name="android.intent.category.BROWSABLE" />
        <data android:scheme="tagmanager.sgtm.c.PACKAGE_NAME" />
    </intent-filter>

</activity>

### build.gradle

implementation platform('com.google.firebase:firebase-bom:33.12.0')
implementation 'com.google.android.gms:play-services-tagmanager:18.3.0'

### We have already attempted the following:

• Uninstalled and reinstalled the application multiple times.
• Cleared Google Play Services data.
• Disabled Private DNS on the device.
• Tested on multiple Android devices with the same outcome.
• Confirmed that play-services-tagmanager:18.3.0 is the latest available version.
• Confirmed that firebase-analytics:23.2.0 is the version resolved by Gradle.
• Added Firebase BOM 33.12.0; no change in behavior.
• Verified that the GA4 data stream is configured with the correct sGTM endpoint.
• Verified that iOS works correctly using the same Firebase, GA4, and sGTM configuration.

Describe the problem

We are unable to reliably see events in the sGTM Preview Mode for Android.

Observed behavior:

Preview mode connects successfully.
Occasionally, standard events such as click and screen_view appear intermittently.
Custom events do not appear consistently or are completely missing.
Event visibility is unreliable and inconsistent across test sessions.
The identical setup on iOS works perfectly, where all events appear in the sGTM Preview debugger in real time.

Both platforms are configured with:

Same Firebase project
Same GA4 property
Same sGTM server URL configured in the GA4 data stream
Same event implementation logic

We have attached the logs collected during testing for reference.

Given the impact on validation and debugging, we would appreciate the opportunity to schedule a call with your team to discuss and troubleshoot the issue.

Are there any known issues with Android Firebase Analytics 23.2.0 and sGTM Preview Mode?

Is the EOFException on 204 No Content responses a confirmed regression in the dynamite module versions listed above, and when is a fix expected?

Steps to reproduce:

Log attached.

firebase_analytics_2.log

Relevant Code:

### Network_security_config file

<network-security-config>
<domain-config cleartextTrafficPermitted="true">
<domain includeSubdomains="false">192.168.1.254</domain>
</domain-config>
</network-security-config>

[dilippatil91]

@google-admin @google-oss-bot
This is a high-priority issue as it is impacting our project deliverables. We would greatly appreciate an expedited review and any guidance from the team on the next steps for investigation and resolution.

[dilippatil91]

Can you please look into this issue
cc: @google-admin

[lehcar09]

Hi @dilippatil91, thank you for reaching out. I tried reproducing the issue, however, I did not encounter the similar error from the logs you shared. Were you able to reproduce this issue in the latest version of Firebase SDK?

[dilippatil91]

@lehcar09 Can you confirm if this is working with the above configuration or with the latest firebase_core: 4.12.1 version?
Also, please confirm which package versions we should use. Do we need to use the latest versions for all packages, or are there specific versions that are recommended?