Why does my Discord bot get Missing Access (50001)?

Fix it in the Discord app

1. Right-click the channel → Edit Channel → Permissions → Advanced permissions. If the channel is synced to its category, right-click the category → Edit Category → Permissions instead.
2. Look at @everyone and at every role the bot has. A red X on View Channel on either one hides the channel from the bot, unless another of the bot's roles has a green check there.
3. Press the plus button, add the bot's role, and set View Channel to the green check. Add what the action needs in the same place: Send Messages and Read Message History to post and read, Manage Channels to edit the channel, Manage Permissions to change who can see it.
4. Press Save Changes, then ask the bot to try again.

Do not fix this by giving @everyone View Channel. That opens the channel to every member of the server, when only the bot needed access.

The rule

Discord lists 50001 as "Missing access" in its JSON error codes. On a channel it is a different failure from Missing Permissions (50013): the bot never got into the channel, so Discord did not look at any other permission. It is also different from Unknown Channel (10003), which is what a channel that no longer exists returns.

View Channel decides whether a channel exists for the bot. Discord's permissions documentation describes it as seeing the channel, reading its messages and joining it if it is a voice channel. Without it, every other permission in that channel is beside the point.

The channel's overwrites decide View Channel. Discord starts from what the bot's roles allow server-wide, then applies the channel's @everyone overwrite, then the overwrites for the bot's roles, then any overwrite for the bot itself. A category's overwrites reach every channel synced to it.

A bot cannot let itself in. It cannot change the permissions of a channel it cannot see, so the allow has to come from a person, or from another bot that can see the channel.

Administrator ignores overwrites. The documentation says it "allows all permissions and bypasses channel permission overwrites", so a bot that has it sees every channel in the server. To see which bots ask for it, read which Discord bots ask for Administrator.

Threads follow their channel. A thread has no overwrites of its own, so a thread inside a channel the bot cannot see is hidden from it too. A private thread is narrower still: Discord's threads documentation says only members added to it, and moderators with Manage Threads, can see it.

If this, then that

• If the bot could see the channel yesterday, someone added a deny or made the channel private. Discord's Private Channel switch takes View Channel away from @everyone, as Discord's Roles and Permissions guide describes, and a bot whose access came through @everyone loses it with everyone else. Add the bot's role to the channel.
• If a whole category went dark at once, the deny is on the category and every synced channel inherited it. Fix it on the category.
• If the bot has Administrator, no overwrite is involved. The ID most likely points at a channel in a server the bot is not in. A deleted channel gives Unknown Channel (10003) instead. Do not change any permission over it.
• If it only fails inside a thread, check the channel the thread sits in. If it is a private thread, add the bot to the thread or give its role Manage Threads.
• If it fails on a whole server rather than one channel, the bot is not in that server. Check the server ID, or add the bot there.
• If it fails when the bot registers slash commands for one server, the app is not installed there with the applications.commands scope. Add the bot to that server with its install link: Discord's application commands documentation says the bot scope includes applications.commands.
• If you are about to deny @everyone View Channel on a category, add a green check for the bot's role first. Otherwise the bot loses the category and every channel synced to it, and has no way to repair that from inside.
• If the error says Missing Permissions (50013) instead, the bot can see the channel and lacks something else. See Missing Permissions (50013).