Teams Android: Crash when using Adaptive Card backgroundImage with fillMode=cover

[MamoruKuroda]

Steps to reproduce

1. Set the Adaptive Card’s backgroundImage to a very small PNG (e.g., 1x1px or 1x3px)
2. Set fillMode to cover
3. Make the card content vertically long (e.g., long text block)
4. Open the card in Teams on Android; the app crashes and reloads as soon as the background image loads

Note:

• If the background image is made vertically longer (e.g., 5x100px), the crash does not occur
• Using fillMode=repeatVertically or repeat prevents the crash

Expected behavior

Teams Android should render the card without crashing, as on PC/iOS, even with small images and long cards.

Actual behavior

On Teams Android, the app crashes and reloads as soon as the background image loads. This does not occur on PC or iOS.

Error details

• Teams Android version: 1416/1.0.0.2025204802/1124
• Calling Version: 2025.34.01.9
• Devices: Pixel 7a, Pixel 8a
• Sample JSON and reproduction video available
• The threshold for crashing (card height/text amount) varies by device

JSON Sample
Please see this 👉 20251203 - example.json

Repro crash
https://github.com/user-attachments/assets/3dba7f39-47e3-4196-9ad2-4ef0da1af2eb

[microsoft-github-policy-service]

Hi @MamoruKuroda! We will investigate and if we require further information we will reach out to you. Please use this link to escalate if you don't get replies in two working days.

Best regards, Teams Platform

[m365-agent-toolkit-assistant]

👋 Hi @MamoruKuroda,

Thank you for reporting this issue! We want to let you know that:

⏱️ Our team will personally review your issue
🎯 You can expect a response within 1 business day

✨ This is an AI-generated initial response
🤖 AI-Generated Preliminary Analysis:

This is a known issue: Adaptive Cards using a small backgroundImage with fillMode=cover may crash Microsoft Teams on Android, especially when the card content is long. Similar rendering bugs have been reported with Adaptive Cards and small/tiled images across Teams mobile platforms.

Recommended Workarounds:

• Use a background image with larger dimensions, especially vertically (e.g., 5x100px), instead of very small (1x1px) PNGs.
• Alternatively, use fillMode=repeatVertically or repeat, which do not trigger the crash.
• For colored strips/effects, consider using a container with a style property or a horizontally repeating (not cover) background image.

References:

• GitHub: Adaptive Card mobile rendering issues
• Stack Overflow: Adaptive Card colored strip workaround

Teams engineering is aware of these limitations, but you can help by reporting via official support channels. Apologies for this bug.

✨We'd love your feedback! Please take a moment to fill out our survey.

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Note: This is an automated first response generated by AI. A human team member will review your issue and provide a more detailed response soon. We appreciate your patience!

[Prasad-MSFT]

Hi @MamoruKuroda, thanks for raising your issue. We will check this at our end and will update you accordingly.

[MamoruKuroda]

Hi @Prasad-MSFT ,
Thank you for your response. If you need more information, please let me know.

[Prasad-MSFT]

Update:

We have raised a bug for this issue. We will inform you once we get any further update from engineering team.
Thanks!