I have been trying to fix this problem on ubuntu running on virtual box (using texmaker and tex live). I have tried this same code on my windows version of latex (running texmaker and Miktex) and it works. For what ever reason I cannot include an image in my document.
fig2 is in the same folder as the tex document, I have had "fig2.png" included there, and what appears to be every other solution out there to fix the problem including "\graphicspath" etc.
Something that may be notable, when I ran it on my windows computer, I executed through terminal, and Miktex automatically downloaded a package which I believe was for include the image. My thoughts are that I am missing something from the Latex package on ubuntu which is stopping it from finding these files.
When I run the code from above with "fig2", the help function returns "could not find files ending in ..." and lists a bunch of files, none of which are .pdf .png or .jpeg.