The presentation delivered by İlyas Teker at the Digitalzone event on October 22, 2016, and shared on his blog today. It can also be downloaded as a PDF.
Magnificent 
Very nice post, thanks! Topic headings I noted while reviewing the slides one by one to remember later:
Technical Errors
- Not noticing that some pages are blocked from Google
- Blocking Javascript and CSS files from Google
- Paying attention to Canonical values
- Indexing filter pages for e-commerce sites to Google
- Unnecessary Tag Pages
- Pages with the same Title and Description
- Forgetting to change robots.txt and noindex tags when moving to a new site.
- Building the site for Robots, not Humans
- High traffic pages giving 404 errors after the new transition
- Non-responsive sites
- Slow loading site, speed issues
- Accidentally deleting all indexes with Search Console
- Detecting a site virus or hack late
- Showing ads to the user before the page
- Redirecting all pages giving 404 errors to the homepage
- 301 Redirect loop
- Hreflang Errors in multilingual sites
Content Errors
- Keyword Stuffing (Stuffing keywords everywhere)
- Indexing pages with little content
- Keeping low-quality (rarely or never visited) pages
- Placing duplicate content
- Creating a separate page for every target keyword.
- Excessive ads
- Putting content that does not appear on the page
- Using texts from other sites exactly. (Like product introductions)
Backlink Errors
- Getting backlinks fast
- It is necessary to get higher quality backlinks instead of more backlinks.
- Backlink source pages returning 404
- Continuing to get backlinks from Directory and Forum sites
- All Backlinks being dofollow
Other errors
- Not using AdWords data for SEO
- Choosing a cheap SEO consultant
Thanks again to İlyas Teker and those who provided these slides.