Excel Graph Displaying Dates as 1900

Excel occasionally has some issues that are not always obvious to solve. This particular one was very difficult and I could not find any solutions that explained it. So I've included here how I solved this particular issue with some helpful screenshots to illustrate it.

1. As you can see the dates on the graph are incorrect. They are showing as 1900. So something is wrong with the data

2. The dates initially looks correct

3.  But converting them to the “General” Format shows some dates are not being converted properly. Excel stores dates as a string of numbers so if the date doesn’t covert to a number when you switch to general there is something wrong with those particular values. 

4.  To fix this double click on each of the cell which didn’t convert to a number and hit enter. Now reconvert all the cells again to “General” Format. You can see then that all the values are being stored properly as numbers. 

5. Select all the cells and convert it back to "Dates." The graph should now be fixed