Unable To Connect To Worlds

Your Microsoft Account connects you to Xbox Live for multiplayer games. On Xbox Live there are Privacy and Online Safety permissions that must be set first to allow cross play. Please review your permissions at Xbox.com. Note that for child (under 13) accounts, a parent must use their account to change the permissions for you.

If this doesn't resolve your problem, please comment with more information. This ticket will automatically reopen when you reply.

Is the issue here affecting Online multiplayer Switch to Switch, or Switch to cross-platform?

Are you able to play other games online on your Switch, and have you tried "Minecraft: Switch Edition" multiplayer before?
I have the exact same issue, but only on the latest 1.4.1 bedrock Minecraft Switch version. 

Just to clarify, I have no knowledge of how to play Switch to Switch outside of Minecraft. To play Minecraft multiplayer --even Switch to Switch-- between a Switch and a non-Switch device, everyone has to have an Xbox Live profile, because the game communicates through Xbox Live. It may be possible to create an Xbox Live account by going to Xbox.com, in which case it's not necessary to open a Microsoft account first. But if you already have a Microsoft account, you can use it to set up your Xbox Live profile without creating a separate account. Once you have the profile, review the Privacy and Online Safety permissions to make sure you can invite your friends and to accept invitations from them. You should also add your friends' Xbox gamertags to your Friends list.

If you run into problems setting up your Xbox Live profile, please contact Xbox Support for assistance. The bug tracker cannot really help you with that kind of problem.

For even more clarification:
deep breath

Switch to Switch play outside of Minecraft, occurs in other games. (No duh.) The process can vary from game to game, but it relatively doesn't change much.
All Switch Online Multiplayer will require a paid subscription by September 2018, (that includes Minecraft). The specifics aren't important, but we're not talking about any rocket science here. The point is that literally every game except this one works with Switch to Switch Online multiplayer.

A) Switch to Switch play does not require a Microsoft account, there is plenty of evidence and past posts by the development team would have most definitely mentioned this. As well as the official FAQ specifically stating that a Microsoft account is required for multiplayer with non-Nintendo devices as well as Marketplace content, realms, servers, etc. Nintendo = Switch. Non-Nintendo ≠ Switch. A Microsoft account is not needed for same platform multiplayer on non-Microsoft hardware. (Fun fact: Every other cross-platform game currently on the Switch doesn't require you to make an account to play on the same console either.)

B) The reason for the question of if this issue was related to cross-platform to Switch or Switch to Switch is relevant as there is an issue pertaining to Switch to Switch not functioning at all, with or without a Microsoft account. Cross-platform play requires an Xbox account, but Minecraft on the Switch does not exclusively rely on Xbox live for communication. (One way you can see this is by being able to see other people playing in the menus without a Microsoft account attached. Another example being that the game does not direct you to get a Microsoft account when attempting to join Switch to Switch, but it does for Switch to cross-platform).

C) If we were to ignore previous and current FAQ's, as well as the in-game guides, manuals, posts from the developers, previously given in and out of game evidence, etc. -When viewing the Profile page on Minecraft (BEDROCK) for the Switch, you can see credentials for your Nintendo account, as well as your Microsoft account. (Provided that a Microsoft account has been attached by that point). Another example being that when a player opens Minecraft on the Switch, it requires your Nintendo Account credentials but does not require your Microsoft credentials. Yet another example being that the Switch can disable cross-platform play, and sometimes is required to when using certain exclusive texture packs. (Namely the Mario Mashup). A Microsoft account running Nintendo exclusive content would probably break some sort of agreement.

D) Even if a Microsoft was is use by both Switch users online multiplayer still cannot function. (MCPE-34846).
Also keep in mind that settings are not responsible here, as Switch to Non-Switch (cross-platform, which requires a Microsoft account) does function. If somebody's settings were screwed up for a Microsoft Account it wouldn't care what device was being used and would block all Online multiplayer. (Even if it did care what device was being used in this way, why would it disable same platform play but not cross-play?)
phew

Thank you, @unknown, for the detailed information. I'm not a Mojang employee so I had no knowledge of the design change to use the Nintendo Switch Online network, and I was unaware that "Switch to Switch" was meant to imply such a connection. I did read the FAQ, but missed the key point you make because it focuses exclusively on playing via a Microsoft account, and the question "What's a Microsoft account and why do I need it for a Nintendo Switch?" implies that you do need one, unconditionally. (It probably would have been better to say "... when do I need it?".) I will modify my comment above based on your explanation.

As this report appears to be about the same issue, I am closing this ticket as a Duplicate of MCPE-34846 due to the latter containing a more detailed description. If you have additional information, please comment there. You may also want to watch that report for updates.

No problem. It is harder to prove technical bugs like this since we don't have access to easy methods of verification. If this was something visual in-game we would have less trouble proving it, as a screenshot would suffice. However since we don't have anything like that, we must do redundant tests and experiments to confirm that this issue is in fact a bug and not something on our end.

和訳してほしい。Please translate into Japanese.

ここに説明の翻訳があります
.
私に参加しようとする人は誰もが世界に出会うことができません。私は私の友達に加わることを試みます私はそれをまた得ます、それは私だけではありません。私はそれがすべて起こっていると聞いています。助けてください。
.
翻訳が間違っている可能性があります。私はGoogle翻訳を使っています

thank you. I understood most parts.