Issue: Unable to post video/photo. Next button not working.
1. Check your internet connection
Whether you admit it or not, internet connection comes one of the biggest reasons for Instagram not posting sometimes. Thus, before you start posting photos or videos to Instagram, make sure you have a great internet connection.
2. Clear the Instagram Cache
There is a big possibility that you cannot post your photos or videos on IG owing to the temporary data stored on your phone. To fix it, you need just reset the app cache data with the following steps:
On iOS device:
Go to "Settings" on your iPhone/iPad.
Tap on "General".
Choose "iPhone Storage".
Tap on "Instagram" app.
Tap "Offload App" to clear the Instagram cache.
On Android device:
Go to "Settings" on your Android phone.
Tap on "Apps" and find the Instagram app.
Tap "Clear Cache" to clear the data cache.
After you've done, open up the Instagram app again to see whether IG allows you to post. If it's not fixed, there may be other problems causing this bug, keep reading...
3. Free up Phone Storage Space
When the storage of your iPhone or Android phone is filled up, you can't upload to Instagram as well. For that, the only thing you need to do is to free up the storage space. Removing some apps that you don't need and transferring photos, videos, music etc. to desktop or cloud services.
4. Change Instagram Data Setting
IG data usage limit can limit what you can upload, how often to post your photos or videos, and how much data is used. If your Instagram post is stuck on sending, it might be an issue that the data limit is set too low. Frankly, raising the limit could get you out of the trouble.
In the Instagram app, go to "Profile".
go to "Settings" and tap "Account".
Scroll down until you find the "Mobile/Cellular Data Usage".
Choose High-resolution media to raise the data limit.