Do most of you are or were programmers or coders?

To be a good Scrum Master does one has to know how to code?

@Martin Premont, The short answer is no, you don't need to know how to code but understanding how software development works is essential, in my opinion. If you know how to code its a bonus as you would have strong technical knowledge to add to your skill set.

I was for a very short period of time a developer.

Hope that helps.

To add to what Steve Vb said - one challenge that can come with having that domain knowledge is remaining neutral as a facilitator and stopping yourself from giving advice or telling the team what you think the solution should be. It's a unique challenge someone with development experience may have to work on but not insurmountable. 

I could see that   Same as a Project Manager you really need to distance yourself of executing the work and to focus on making sure the project work gets done instead of product work.

Not a developer or coder at all here. My teams would say I'm an effective SM. I know enough of the dev side to help the team and I continue to grow in my knowledge and understanding but I have no plans to become a developer and it doesn't mean I cannot be a SM.

It is not important to have development experience to be scrum master. Scrum master just need to be experienced in scrum. I would insist that having development experience while leading a technical team could be an important factor. It would be easier for scrum master to understand, analyse transparency, quality, guide and even collaborate in technical discussions. 

I have seen scrum masters with almost no industrial experience leading technical teams. though they did what a scrum master is expected to do but they also struggled in understanding day to day development issues and tasks. 

I started as a COBOL developer in 1986, started QA in 1997 and did little bits of coding my entire career.  But I don't think it is necessary. And as others have pointed out, it can be problems for some. I know a couple of Scrum Masters with no coding background that are fabulous.  I know a couple of coders that became Scrum Masters that were not effective and gave up because they could not distance themselves from the technical problems and focus on the team building side. 

There are some other threads in this forum on this exact subject Here is one search that brings up a few of them:https://www.scrum.org/search/content?keys=technical%20background&f%5B0%5D=type%3Aforum&advanced-form=1.  I'm pretty sure you will see a common thread.  Technical knowledge isn't needed, can be useful but can also be a hindrance.

I completed a PhD in object-oriented rapid prototyping in 1997, and wanted to be a transformation consultant. I then had to work as a Java developer for several years though, since no employer believed it remotely plausible to evolve increments of software in 2-6 weeks.

I have never written a line of code in my life.  I spent 24 years in the military doing mainly construction and heavy engineering projects.  I fell into Scrum when I left and I think the teams that I currently work with and my previous teams would say that I am highly effective as a SM due to not having the technical background.  In my experience I have found that some scrum masters who come from a development/QA background tend to have an input on the solution, thereby not allowing the team to be self-organising (Just my experience).

I just started at a company where I've taken over as Scrum Master from people who were part-time Scrum Masters, part-time developers or technical leads.

What they expressed was that Scrum Master often took a backseat to development, and they found themselves going down rabbit holes of technical minutiae instead of stepping back to look at the bigger picture.

I have never been a programmer or coder and have a basic knowledge of programming. A lot of the technical language in our sprint ceremonies is a mystery to me.

However, I have the advantage of being able to ask questions and step back and look a level above for what's really going on. I can challenge the team to become self-sufficient ("Why did that happen? Who can help solve that?") instead of the temptation of providing answers for them.

And it challenges me to build relationships with a network of experts to go to when the team does have questions they can't solve themselves.

I have been a Scrum Master for years without ever being a developer or having that type of technical knowledge. Nearly all of the Development Teams that we have spoken with on what they look for in a Scrum Master seemingly have boiled down to the following:

• Mindset
• Comfortable having difficult conversations 
• Non-technical (not a developer)