If it's Samsung's Messaging app, download Google Messages from the Play Store & set it as your Default Messaging app.
If it's Google Messages, go to Settings > Apps Search Google Messages & Click on it & Scroll down to Storage & Clear Both Cache & Data for the app & Reboot
You WILL NOT LOSE your Messages, they will be repopulated by your Carrier automatically.
Hi, if your'e using Samsung messages app, we recommend you to use Google messages instead of preloaded Samsung messages app. Samsung has joined with Google on a common messaging client as a default messaging app.
Please download Google messages and set it as a Default messaging app.
Also, as adviced by RedDogRabbit, please perform Clear cache and Clear data for the messaging app and check for the issue.
