In both Magento 1 and Magento 2 you may see an error on the top of the screen indicating that you need to run your Index Management.
For Magento 1, it looks similar to this.
The Magento database needs to be re-indexed from time to time. While index management runs automatically, sometimes it need to be run manually to get products or images to appear online right away. This error simply means that the Magento database that holds all of your data and images is slightly out of balance.
You can easily fix this by going to System > Index Management
Once the Index Management screen opens. Click the Select All button on the top far left.
Then click the Submit button on the top far right
You may need to run this process more than once.
Once the process is finished your screen should look similar to the one below.