"Warning 000258: Item Already Exists" when creating feature classes, buffers, clips, etc.

[JPalmer]

Hi everyone,

I am a beginner in using ArcGIS Pro and have been learning to do some basic geoprocesses and map making through online guides. I am trying to calculate percent of impervious land by plotting a point (study site), creating a buffer around it then using the Pairwise Clip tool to isolate the geodata for that buffer/site. I've successfully done this once (with the exception of my shape area of a 300m buffer not matching the area of of a circle with r=300) but am running into some issues.

I am trying to do the same process, but whenever I create a new buffer, I am met with "Warning [buffer name] already exists" so this doesn't generate anything. I've tried deleting old feature classes from my catalog, refreshed it and restarted the application. I've also gone into my files and have deleted the entire project folder including the gdb to start from scratch. Within a whole new project, I am met with the same warning messages. 

Any idea what could be causing this?

[Robert_LeClair]

So this warning message that "by default, tools are not allowed to overwrite existing output datasets with the same name" according to the Tool Reference sheet.  What you can do is go to the Project->Options and in the Application group, click Geoprocessing.  Then check the box for "Allow geoprocessing tools to overwrite existing datasets" - see image below: