Grid Pattern Visible in High ISO Image

Whilst this is a 2 year old thread, there's something that hasn't been mentioned. 

Lens Corrections -the distortion setting introduces visible geometric artifiacts that are more noticable with high ISO images. Mine defaults to 100. Setting the Distortion amount to zero removes the visible pattern.

Here's is an example of that visible pattern for a section of dark night sky. Distortion = 100.

I see the grid pattern. This is almost definitely caused by the image sensor in your camera.

You included the actual image in your attachment. Size 21.96MBs. I'm not sure you can include that size image in with the text of your post and since it is the actual image does not display what You are Seeing on your screen.

To me I do not see any Grid Pattern. I do see Noise and yes the ISO is very high, 3200, This is what I see on my screen @ a 2:1 zoom.

Please Edit you post to remove the Attached screen shot and Include it in the body of the text of your post.

You do that by Clicking the "More..." link at the bottom of your post, Selecting "Edit Message" and then use the "Insert Photos" icon in the tool bar at the top of the Post/Reply/Edit dialog box like this.

Also, please consider editing your first post, and instead of attaching the photo, insert it.

What time was the images shot? full dark? if so, why blue sky?

I do not see the grid. I do see lots of noise, high iso, dark sky, etc.

How  much post processing was done? A couple of assumtions, some global as opposed to local editing was done to bring up a dark scene, perhaps use more local processing as to avoid doing much to the sky, do not sharpen the sky.