White lines after exporting to PDF from Illustrator
Hi everyone, I apologize initially for possible grammatical errors.
As written in the title, when I go to export to pdf from illustrator, white lines appear that follow the segments of the illustration.

In illustrator, however, the file is perfect.

I tried to read and do all the tests that I found in this forum, in others and followed a thousand other tips (such as disabling or changing the anti-aliasing settings). The only real solution I have found is to open the polygons in order to place them under others (placed in the foreground). Now, I'm still a beginner with Ilustrator and I probably did something that I shouldn't have.
In my opinion, the problem was created because, once I made a polygon over the initial shape, I then went to use the white arrow (A) to drag an anchor point over an already existing one ... in fact going to expand the segments in so that they are no longer "precise" the white lines disappear.
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Can you recommend a method to solve everything as quickly as possible? Because I tried to enlarge the polygons by hand and it works but I have to fix 10 illustrations all composed of a myriad of polygons.
Edit: I'm using Windows 10 pro and Illustrator is the latest version avaible
Edit 2: 
I tried to export the file in .tiff and instead of the lines it seems that a blurred halo appeared ...
they are always better than before but it is not perfect and it is not a pdf
Last Edit:
I tried to duplicate the layer, copy it to one below and convert it to grayscale and now I tried to export it to pdf and it seems ok
... at least .. it is for me haha

