Where can I find the official list of supported file upload extensions for Teams?

[gauravsarwal]

I am trying to find a clear Microsoft document that outlines the supported file types and maximum upload limits for Microsoft Teams chats and channels. I cannot find any direct documentation that explicitly lists which extensions are allowed or if certain formats (like executables or compressed files) are blocked by default. Could someone please point me to an official reference link or provide clarification on the current file size restrictions? Thanks in advance!

[microsoft-github-policy-service]

Hi @gauravsarwal! 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 gauravsarwal,

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:

Classification: Not a bug — Teams doesn’t maintain a single universal extension allowlist; file handling follows Teams, SharePoint, OneDrive, and tenant restrictions.

• Private chat: maximum 10 attachments, 100 MB per file.
• Channel Files tab: SharePoint-backed, with a 250 GB per-file upload limit.
• Most file types are supported, but invalid names, malware detection, or organization-specific policies can block files. Executables or archives aren’t universally blocked by Teams by default.

What to do now:

1. Use the Teams limits page for chat and channel size limits.
2. Check SharePoint/OneDrive restrictions and tenant policies for blocked extensions.
3. If a specific extension fails, record the upload route, exact error, and tenant policy.

Useful links:

• Teams limits and specifications
• OneDrive and SharePoint restrictions
• No sufficiently relevant related issue found in the searched repos.

---

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!

[sayali-MSFT]

Hello gauravsarwal ,
Yes. Microsoft now has official documentation for both the file-size limits and the file types that Teams can block.

• Teams chat attachments: Maximum 100 MB per file, with up to 10 file attachments per chat message.
  https://learn.microsoft.com/en-us/microsoftteams/limits-specifications-teams
• Files uploaded to a Teams channel / Files tab: The underlying storage uses / , and the documented individual file upload limit is 250 GB.
  https://learn.microsoft.com/en-us/office365/servicedescriptions/sharepoint-online-service-description/sharepoint-online-limits
• Blocked file types: Teams has Weaponizable File Protection, which can block potentially unsafe extensions in chats and channels. The Microsoft documentation explicitly lists extensions such as .exe, .bat, .cmd, .dll, .msi, .vbs, .iso, .jar, .docm, and others. The blocked-extension list itself isn't administrator-configurable.
  https://learn.microsoft.com/en-us/microsoftteams/weaponizable-file-protection-teams
• This protection is controlled through Teams Admin Center > Messaging settings > Messaging safety > “Scan messages for file types that are not allowed.”
  https://learn.microsoft.com/en-us/microsoftteams/weaponizable-file-protection-teams

Official Microsoft references:

1. Limits and specifications for Microsoft Teams
2. SharePoint limits, including the 250-GB file upload limit
3. Weaponizable File Protection in Microsoft Teams, including the blocked-extension list

[gauravsarwal]

sayali-MSFT Thanks for sharing the links.

[microsoft-github-policy-service]

Tell us about your experience!

Hi @gauravsarwal! This issue is closed in our system. We would like your feedback on your experience with our support team and Platform.

Best regards,
Teams Platform

[gauravsarwal]

sayali-MSFT Can you share from Task dialog what is maximum size allowed as I did not find it links shared. I am not sure what will happen if someone upload a file of size 1 GB, Teams will allow it or give time out error.

[microsoft-github-policy-service]

Hi @gauravsarwal! 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