When Microsoft Teams or Slack crashes during a meeting or at a critical moment, it affects your entire workday. These apps are mission-critical for millions of remote workers in 2026 — and when they fail, you need a fix right now.
This guide covers the most effective fixes for both apps on iPhone and Android, plus how to prevent crashes before they happen.
Microsoft Teams Crashing on Mobile: Fastest Fixes
Fix 1: Clear Teams Cache
Teams stores meeting recordings, chat history, and file thumbnails in cache. Over time, this cache can become corrupted and cause crashes:
Android:
- Settings → Apps → Microsoft Teams
- Storage & Cache → Clear Cache
- Relaunch Teams
iPhone:
- Open Teams → tap your profile picture
- Go to Settings → Clear App Data (at the bottom)
- Confirm and restart the app
Fix 2: Update Microsoft Teams
Microsoft pushes Teams updates weekly. Security policies in enterprise accounts often require the latest version — older versions are actively blocked:
- Android: Google Play → My Apps → Update Teams
- iPhone: App Store → Your Profile → Update Teams
Fix 3: Sign Out and Sign Back Into Teams
Microsoft 365 authentication tokens expire regularly. If Teams crashes specifically when opening or joining meetings, your token may be stale:
- Open Teams → Profile Picture → Sign Out
- Wait 1 minute
- Sign back in with your Microsoft 365 email and password
- Complete any MFA (multi-factor authentication) prompts
Fix 4: Check if Teams is Blocked by Your VPN
Many corporate VPNs route Teams traffic through servers that can’t handle real-time audio/video. If Teams crashes during calls but not in chat, temporarily disable your VPN during the meeting and re-enable it after.
Slack Crashing on Mobile: Fastest Fixes
Fix 1: Force Stop and Restart Slack
- iPhone: Swipe up → swipe Slack off the screen → reopen
- Android: Settings → Apps → Slack → Force Stop → reopen
Fix 2: Clear Slack Cache and Data
Slack caches every file and image shared in channels. After months of use, this cache can reach several gigabytes and cause serious slowdowns:
- Open Slack → tap your workspace name
- Go to Preferences → Advanced
- Tap Clear Cache
On Android: Settings → Apps → Slack → Storage → Clear Cache
Fix 3: Update Slack
Slack releases frequent security and performance updates. On enterprise accounts, your IT admin may require a minimum version. Running an older version will cause login failures and crashes.
Fix 4: Reduce Notification Settings
Slack crashes are often triggered by notification overload — channels with thousands of unread messages processing all at once. Reduce this by:
- Go to Preferences → Notifications
- Set most channels to @ mentions only
- Mute non-critical channels
Fixes That Work for Both Teams and Slack
Free Up Phone Storage
Both apps struggle when internal storage is under 1 GB. Go to Settings → Storage and clear space if needed. Check our guide on which apps consume the most storage and battery.
Check Your Work Network
Corporate firewall settings sometimes block Teams or Slack video calls on certain ports. If both apps work fine on home Wi-Fi but crash at the office, ask your IT department about firewall exceptions for ports 443, 80, and 3478.
Reinstall as Last Resort
- Uninstall the crashing app
- Restart your phone
- Reinstall from App Store or Google Play
- Sign in with your work credentials
Preventing Future Crashes
- Enable auto-update for Teams and Slack so they always run the latest version
- Set a weekly reminder to clear cache in both apps
- Keep at least 2 GB free storage on your phone at all times
- Before important meetings, close all other apps and ensure strong Wi-Fi connection
Frequently Asked Questions
Why does Microsoft Teams crash during video calls but not in chat?
Video calls require significantly more processing power and bandwidth than text chat. Crashes during calls usually indicate insufficient RAM, a weak internet connection, or a VPN throttling the video stream. Try turning off your camera during calls to reduce the load.
Why does Slack keep crashing when I open certain channels?
Channels with thousands of messages or large file attachments can overload Slack’s mobile rendering engine. Clear the app cache, and ask your workspace admin to archive very old channels to reduce the load.
Can I use Teams and Slack on the same phone without issues?
Yes, but both apps compete for background resources. Make sure only the app you’re actively using has notification access and background refresh enabled. Disable background refresh for whichever app you use less frequently.