Discord permission checker: roles, channels and 50013 errors

The bot cannot assign a role

Check the bot’s role
In Server Settings → Roles, select the bot’s role and check Manage Roles. Ask a server administrator to grant only the permissions this feature needs.
Check the role order
Move the bot’s highest role above the role it needs to assign. An equal or higher role cannot be assigned, even with Administrator. You do not need to put the bot above every staff role.
Choose an assignable role
Use a normal server role. Roles managed by an integration or subscription cannot be assigned manually by a bot, and @everyone is not an assignable member role.

Only a server administrator should change these settings. Retest the affected feature after each change. Do not grant Administrator as a shortcut.

Check access to the target channel
Open the target channel’s permissions. Check your roles, the bot’s roles and any member-specific overrides. Also check the category if the channel inherits its permissions.
Check Manage Roles in the channel
Editing or deleting a channel permission overwrite requires Manage Roles. Manage Channels alone is not enough. acrO checks the invoking user and the bot in the target channel; its server-wide lock option also requires Manage Server for the user.
Check the affected permission flags
Discord limits which permissions a bot can allow or deny in an overwrite. Check the flags affected by the command, such as Send Messages, in the target channel. Follow the bot’s missing-permission message instead of granting Administrator. If members can still write, inspect other role and member overrides; administrators bypass channel overwrites.

Only a server administrator should change these settings. Retest the affected feature after each change. Do not grant Administrator as a shortcut.

Check the destination and visibility
Confirm the configured channel still exists. In its permissions, check View Channel for the bot, including role and member overrides. Permissions on a different channel do not prove access here.
Check sending permissions
For a normal text channel, check Send Messages. Threads use Send Messages in Threads and may also need membership or reopening if archived or locked. Check the parent channel’s permissions too.
Check the message format
Rich embeds need Embed Links; uploaded images and files need Attach Files. Grant these only where the bot needs to post that content. A plain-text message does not need both.

Only a server administrator should change these settings. Retest the affected feature after each change. Do not grant Administrator as a shortcut.

Check installation and command availability
Check Server Settings → Integrations and the bot’s command list. A user-installed app is not the same as a server-installed bot. A missing command may be disabled, unavailable in this context, or not registered by the developer.
Check Discord command restrictions
Check Use Application Commands in the channel and the app’s command restrictions under Server Settings → Integrations. Commands can be limited to particular roles, members or channels.
Check runtime authorization too
Making a command visible in Integrations does not bypass the bot’s security checks. acrO still checks the user and bot permissions for the operation. For example, slowmode needs Manage Channels, purge needs Manage Messages, and timeout needs Moderate Members; moderation can also be limited by role hierarchy.

Only a server administrator should change these settings. Retest the affected feature after each change. Do not grant Administrator as a shortcut.