When you did not highlight the selected button.
We always have to highlight the selected button to know where we are. Many designers forget or fail to highlight the button which is selected on the navigation bar, Users need a visual feedback on what they choose or selected when they click on it.
They might mistake it for some other page if they are not directed where they are n their task flow. So use color contrast as well as shape to highlight the selected button.
Normally, a standard way to highlight the button or shape is to make it underline under the label or an outline.
But highlighting it in the navigation bar makes it extra clear to prevent any confusion.
Selected button having low color contrast.
Many websites use low color contrast to differentiate between the selected buttons which is a mistake because it confuses users in recognizing where they are in the site hierarchy.
Low color contrast makes it difficult for the user to read the button label. This forces the user to recall what they clicked earlier. It’s always faster if users can recognize the selected button by visualizing.
The selected button should have the highest color contrast of all the buttons. This makes the users recall the currently active button quickly.
Low Color Contrast on Inactive Buttons
The buttons which are not in use or which the user is not gonna select should always be in lower contrast. But not very low that the labels are hard to read. Sometimes when the contrast is too low on buttons makes the users forget or miss them. They might think that they are disabled.
Not Making Area Around the Label Clickable
Navigation bar buttons have whitespace around it which separates it from other buttons on the websites. This will give the buttons some space and a larger click target so that users can navigate faster.
No Hover and Focus Effect on Buttons
When you put the hover effect on the navigation button which will make it easier to click. This makes the user realize or know when the mouse cursor is in a clickable area. Without the effect, users always assume and hit click to activate the button.
Not every user uses a mouse, some might use the keyboard to navigate and they need to focus on the tab effect between options.