Messages are slow, do not send, or cannot be received on Samsung phone

To inspect the device for physical damage:

• Look for scratches, cracks, or other damage on the front and back of the device. Obvious cracks on the screen are usually due to an impact on the front of the device. 
• If the device has a round spot of dead pixels, it may have been subjected to a more gradual pressure that left the front glass intact, while damaging the screen underneath.
• Ensure the connectors in the charging port are not corroded, bent, broken, or pushed in. If you have a removable battery, check the battery connectors as well.

To inspect the device for liquid damage, check the LDI (Liquid Damage Indicator) located either inside the SIM card tray slot for newer devices or on the removable battery for older devices.

First, power off the device. For newer devices, insert the ejector tool that came with your device into the hole on the SIM card tray, and then push the tool until the tray pops out. For older devices with a removable battery, remove the back cover.

Important: Be careful not to insert the ejector tool into any of the microphone or speaker holes along the edge of your device. Look for the outline of the tray to make sure you're in the right place.

Look inside the slot to access the LDI. If your device has a removable battery, take out the battery and inspect it. LDI indicators should be solid white or white with visible pink or purple X's. If the device has been exposed to moisture, the LDI will be solid pink, purple, or red.

With the SIM card tray removed, make sure that the SIM card is lined up with the smaller cutout on the SIM card tray. If your device has a removable battery, make sure the SIM card is lined up with the designated slot. The orientation of the metal contacts will vary by device. The SIM card will only fit correctly in one direction.

Verify the card is flush with the tray, then insert the SIM tray back into your device. If your device has a removable battery, push the SIM card into its designated slot, and then replace the battery and the back cover. Now, power on your device!

1. On your device, navigate to and open Settings.
2. Swipe to and tap Software update or System updates. It will vary between models.
3. Tap Download and install or Check for software updates. If an update is available it will begin downloading, though you may need to tap Download now on some devices.
   
   
4. When the download is complete, follow the on-screen instructions to install the update.

You can also check for updates using Smart Switch.

• Make sure the phone or tablet is connected to the internet and charged to at least 50% before installing a software update.
• Some carriers require a Wi-Fi network connection and will not allow you to update using mobile data.
• If an error occurs during a software update and your phone or tablet keeps restarting, learn how to get out of a boot loop.
• If your phone or tablet doesn't have enough storage space, you can clean up your storage with Device care. You can also back up extra files using Smart Switch or your Samsung or Google account.

If you were having issues before the software update, use the phone or tablet normally to check if the problem has been solved.

Certain downloaded apps can make your phone or tablet freeze, crash, or lag. Some apps can even affect camera functionality, cause audio issues, and affect network connectivity.

Using Safe mode disables all downloaded apps and loads only the original software that came with your phone or tablet, allowing you to determine if the issue is caused by an app or with the device itself.

If the issues do not appear while in Safe mode, the problem is caused by a downloaded app, and it should be uninstalled.

First, open the Power menu:

• On devices with a regular Power button, press and hold the Power button until the Power menu is displayed.
  
• On devices without a dedicated Power button, swipe down from the top right of the screen to open the Quick settings panel. Tap the Power icon at the top of the screen.

Touch and hold Power off until the Safe mode icon is displayed. Tap Safe mode to start your device in Safe mode. If you've entered Safe mode successfully, you'll see “Safe mode” displayed at the bottom of the screen.

Use the phone or tablet normally to see if the issue has been resolved. If the phone or tablet is operating normally, a recently installed app was most likely causing the issue.

• If the issue is gone in Safe mode: One of your recently downloaded apps was likely the cause of the problem. Proceed to Step 4.
  
• If the issue still exists: Downloaded apps may not be the cause of the problem. You may need to reset the phone or tablet to its factory setting.

One by one, uninstall any apps you downloaded just before your phone or tablet began having the issue.

From your Home screen, swipe up to open the App drawer. Find the app you want to remove, and then touch and hold the app's icon until a popup menu appears. Tap Uninstall, and then tap OK to confirm.

After uninstalling each app, exit safe mode and check for normal operation.

After you uninstall the app that caused the issue, you can reinstall the other safe apps you just deleted.

First, open the Power menu:

• On devices with a regular Power button, press and hold the Power button until the Power menu is displayed.
  
• On devices without a dedicated Power button, swipe down with two fingers from the top of the screen to open the Quick settings panel. Tap the Power icon at the top of the screen.

Tap Power off to turn off the device. Wait until the phone or tablet completely turns off, and then press the Power button again to turn it on. Check if the issue has been resolved.