Black background color tooltips in Eclipse Oxygen

Create a new Workspace and import the projects again . Worked fine for me . I faced the issue on Mac , Eclipse Oxygen . I tried adding the Darkest Color theme and since then this problem started . I changed the workspace and reimported my projects again .

Go to Window->Preferences -> General -> Appearance -> Colors and Fonts. Type in the filter "javadoc". Select Javadoc background and click on Edit. You can select the background color there

Here's what solved the problem for me on Eclipse 2018-19 (SimRel). I did it by changing the theme from the eclipse menu by going to :

Window -> Preferences -> Clicking on the Appearance option -> Changing the Colors and Fonts to something else.

For me, I had to change it from the reduced palette to the windows default.