> ## Documentation Index
> Fetch the complete documentation index at: https://cometchat-22654f5b-docs-ios-ui-kit-sdk-fixes.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.
# Constraints, Rate Limits And Errors
### Properties and Constraints:
#### **API Keys: Properties and Constraints**
| **Item** | **Property or Constraint** | **Notes** |
| ---------------------------------------------------------- | ----------------------------------- | ------------------------------------------------------------------------------- |
| API Keys | 100 characters (UTF8mb4 Characters) | This covers all the languages and even emojis. (One emoji uses two characters). |
| Maximum number of APIs keys that can be created for an app | 25 | Contact support if you need additional API keys for your application. |
#### **Users and Groups: Properties and Constraints**
| **Item** | **Property or Constraint** | **Notes** |
| ----------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ------------------------------------------------------------------------------------------------------------------------------ |
| Character limits for UIDs and GUIDs | 100 characters | Use alphanumeric characters with dashes only; spaces are not allowed. |
| Maximum users in a group (with all features) | 300 | Groups up to 300 members support all features including delivery/read receipts and typing indicators. |
| Maximum users in a group (without delivery & read receipts) | 50,000 (up to 10,000 concurrent) | Large groups disable delivery/read receipts and typing indicators for performance. |
| Maximum groups a user can be a part of | 2000 | Users exceeding this limit must leave existing groups before joining new ones. |
| Maximum number of friends for a user | 1000 | Friend relationships are bidirectional and count toward both users' limits. |
| Maximum tokens for a user | No limits | Multiple auth tokens allow users to stay logged in across different devices. |
| Maximum Number of Bot users that can be created | 25 | Bot users are special accounts for automated messaging and integrations. |
| Bot UID character limit | 50 characters | Bot UIDs have a shorter limit than regular user UIDs. |
| Maximum number of groups | No limits | Create as many groups as needed; billing is based on active users. |
| Maximum number of unread messages per user | No limits | Unread counts are tracked per conversation for accurate badge displays. |
| Maximum number of users that can be created for an app | No limits | User creation is unlimited; pricing is based on Monthly Active Users (MAU). |
| User and Group ID | 100 characters, alpha-dash (a-z, 0-9 with -and \_) without spaces . | CometChat forces the UID to all lowercase. |
| User and Group name | 100 characters, UTF8mb4 set | This covers all the languages and even emojis. |
| User and Group avatar | Must be a URL, limit of 3000 characters | CometChat doesn't save the image on its servers.. There is no limit on the image resolution. It depends on the implementation. |
| User profile | Must be a URL, limit of 3000 characters | Same as above |
| User and Group metadata | The API limit for the POST request length is 10 KB. Hence, the user's metadata information must fit in the same limit and must not exceed 5 KB. | Use metadata to store custom key-value pairs for users and groups. |
| User and Group tag | A user can have up to 25 tags with 100 characters per tag. The tags can be in any language. The character set must be UTF8mb4 | Tags enable filtering and searching users/groups by custom categories. |
| Group password | String up to 100 characters | Only applicable for password-protected group types. |
| Group description | 255 characters, UTF8mb4 set | Provide a brief summary of the group's purpose for members. |
| Maximum active presence subscriptions | The presence subscription will be active until 1000 users are online for a single app. if more than 1000 users go online, the presence notification starting from the 1001st user will not be sent to other users. | Note, this is the higher limit applicable across subscription for friends, users with certain roles and all users |
| Typing indicators for groups | Typing indicator will be sent for a group of up to 1000 online users. | Disabled for larger groups to optimize real-time performance. |
| Unread message counts for groups | For a group with more than 300 members, the conversations and unread message counts are not updated. | Use message history APIs to track read status in large groups. |
| Delivery and read receipts for groups | Delivery and read receipts will be sent for a group of up to 300 online users. | Receipts are disabled in large groups to reduce server load. |
#### **Roles: Properties and Constraints**
| **Item** | **Property or Constraint** | **Notes** |
| ------------------------------------------- | ----------------------------------------------------------------- | ------------------------------------------------------------ |
| Maximum number of Roles that can be created | Maximum 25 | Roles define permissions and access levels for users. |
| Role UID | 100 characters, alpha-dash (a-z, 0-9 with -and \_) without spaces | CometChat forces the UID to lowercase. |
| Role name | 100 characters, UTF8mb4 | This covers all the languages and even emojis. |
| Role description | 255 characters, UTF8mb4 set, any language. | Describe the role's purpose and permissions clearly. |
| Metadata | No limit | Store additional role configuration as JSON key-value pairs. |
#### **Messages: Properties and Constraints**
| Item | Property or Constraint | Notes |
| ----------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------- |
| Maximum message size | 65 KB (\~65,536 characters including metadata) | Total size limit for the entire message payload. |
| File size | Maximum file size per message: 100 MB | Applies to the uploaded file associated with the message. |
| Message Data | Arbitrary JSON (UTF-8/utf8mb4), up to 10 KB for the data object; keys with special meaning to CometChat: `text`, `attachments`, `customData`, `metadata` | Attachment properties (for example, URL and size) can be included here; the actual file limit is defined under File size. |
| Groups → Unread message count | For groups with more than 300 members, conversation and unread message counts are not updated | Use message history APIs to track read status in large groups. |
| Groups → Mark as unread | For groups with more than 300 members, the unread message counts are not updated | Feature disabled for performance optimization in large groups. |
| Groups → Message receipts | Delivery and read receipts are sent for groups with up to 300 members | Receipts are disabled in large groups to reduce server load. |
| Tags | Up to 25 tags per message; 100 characters per tag (UTF-8/utf8mb4) | Tags can be in any language. |
| User mentions | Up to 10 distinct users can be mentioned in a message | Format: `<@uid:{uid of the user}>` (example: `<@uid:cometchat-uid-1>`). |
| Reactions | Maximum 25 distinct reactions per message; reaction text up to 45 characters (UTF-8/utf8mb4) | Character counts are by Unicode code points. Emoji are supported and may use multiple code points. |
#### **Calling: Properties and Constraints**
| **Item** | **Property or Constraint** | **Notes** |
| ---------------------------------- | ------------------------------ | ----------------------------------------------------------------------------------- |
| Maximum users in a call | 50 | Supports both one-on-one and group calling scenarios and it works the best with 50. |
| Default frame rate for video calls | 30 FPS | Frame rate may adapt based on network conditions. |
| Resolution for video calls | Maximum - 720p, Minimum - 180p | This depends on the layout selected and the bandwidth available at the user's end |
| Media encryption used | SRTP | Ensures secure real-time communication for all calls. |
| Audio codec used | OPUS | Optimized for low-latency voice communication. |
| Video codec used | H.264 | Widely supported codec for cross-platform compatibility. |
#### **Webhooks: Properties and Constraints**
| **Item** | **Property or Constraint** | **Notes** |
| ------------------------------- | --------------------------------------------------------- | ----------------------------------------------------------------- |
| Webhook URL | Valid URL, maximum 255 characters | Must be a publicly accessible HTTPS endpoint. |
| Webhook ID | 50 characters, UTF8mb4 set, alphanumeric (without spaces) | Unique identifier used to manage and reference the webhook. |
| Webhook authentication username | 50 characters, alphanumeric (without spaces) | Used for HTTP Basic Authentication when calling your endpoint. |
| Webhook authentication password | 100 characters, alphanumeric (without spaces) | Keep this secure; used to verify webhook requests to your server. |
### Rate Limits
| **Operation Type** | **Rate Limit** | **Examples / Notes** |
| ------------------- | ------------------- | ---------------------------------------------------------------------------------- |
| Core operations | 10,000 requests/min | User connection, create/delete user, create/join/leave group |
| Standard operations | 20,000 requests/min | All other operations (sending messages, fetching conversations, updating profiles) |
| Build plan (free) | 500 requests/min | Applies to both core and standard operations |
| Send message | 30 messages/min | Per user rate limit for sending messages |
| Mark as unread | 5 requests/min | Per user rate limit for marking messages as unread |
| Data import | 60 requests/min | Rate limit for bulk data import operations |
### Errors
| Error Code | Error Description |
| ----------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Auth Errors** | |
| `AUTH_ERR_EMPTY_APPID` | Indicates empty appId in the headers. |
| `AUTH_ERR_INVALID_APPID` | Indicates invalid appId or it does not exist in a region. |
| `AUTH_ERR_EMPTY_APIKEY` | Indicates empty API Key in the headers. |
| `AUTH_ERR_APIKEY_NOT_FOUND` | Indicates incorrect API Key in the headers. |
| `AUTH_ERR_NO_ACCESS` | Indicates API Key in the headers can not be used to perform the action.
For example, the API key with authOnly scope cannot be used to create a user. |
| `AUTH_ERR_EMPTY_AUTH_TOKEN` | Indicates empty auth token in the headers. |
| `AUTH_ERR_AUTH_TOKEN_NOT_FOUND` | Indicates incorrect auth token. |
| **API Key Errors** | |
| `ERR_APIKEY_NOT_FOUND` | Indicates that the api key does not exists. |
| `ERR_APIKEY_NO_SELF_ACTION` | Indicates that the API key in the headers is same as the API key in the path param and it is performing action on it self.
The API Key should not update/delete itself. |
| **Auth Token Errors** | |
| `ERR_AUTH_TOKEN_NOT_FOUND` | Indicates that the auth token does not exists. |
| `ERR_AUTH_TOKEN_DELETE_FAILED` | Indicates that the API failed to delete the auth token. |
| `ERR_AUTH_TOKENS_DELETE_FAILED` | Indicates that the API failed to delete the auth tokens associated with the UID |
| `ERR_AUTHTOKEN_UNAVAILABLE` | Indicates that the auth token is mapped with another device. |
| `ERR_AUTHTOKEN_NOT_ACCESSIBLE` | Indicates that the auth token is mapped with another user. |
| **Subscription Errors** | |
| `ERR_PLAN_RESTRICTION` | Indicates that the feature is not available with the plan. |
| `ERR_SUBSCRIPTION_EXPIRED` | Indicates that the subscription has expired and must resubscribe to continue using the service. |
| `ERR_PLAN_QUOTA_RESTRICTION` | Indicates that the allowed limit for the feature has reached. |
| **Role Errors** | |
| `ERR_ROLE_NOT_FOUND` | Indicates that the role does not exist. |
| `ERR_ROLE_DELETE_FAILED` | Indicates that the API failed to delete the role. |
| `ERR_ROLE_DELETE_DENIED` | Indicates that the API cannot delete the role as the default role can not be deleted. |
| **User Errors** | |
| `ERR_UID_NOT_FOUND` | Indicates any one of the following:
1. UID does not exist.
2. User is soft deleted. |
| `ERR_UID_DELETE_FAILED` | Indicates that the API failed to delete the user. |
| **Bots Errors** | |
| `ERR_BOT_NOT_FOUND` | Indicates that a bot is not associated with the UID. |
| `ERR_BOT_ALREADY_EXISTS` | Indicates that a bot is already associated with the UID. |
| **Group Errors** | |
| `ERR_GUID_NOT_FOUND` | Indicates that the GUID does not exist. |
| `ERR_EMPTY_GROUP_PASS` | Indicates one from the below:
1. Empty password for password type group to create group API.
2. Empty password for pasword type group to join group API. |
| `ERR_GROUP_DELETE_FAILED` | Indicates that the API failed to delete the group. |
| `ERR_NOT_A_MEMBER` | Indicates that the user is not a member of the group. |
| `ERR_WRONG_GROUP_PASS` | Indicates password mismatch for the password type group. |
| `ERR_ALREADY_JOINED` | Indicates that the user has already joined the group. |
| `ERR_GROUP_NOT_JOINED` | Indicates that the user is trying to access the group feature without joining it. |
| `ERR_GROUP_JOIN_NOT_ALLOWED` | Indicates that the user is trying to join the private group. |
| `ERR_MEMBER_DELETE_FAILED` | Indicates that the API has failed to remove a user from the group. |
| `ERR_NO_VACANCY` | Indicates that the group is full. |
| `ERR_SAME_SCOPE` | Indicates that the existing and new scope are same. |
| `ERR_MEMBER_SCOPE_CHANGE_FAILED` | Indicates that the has failed to change the scope. |
| `ERR_NOT_A_BANNED_USER` | Indicates that the API is trying to unban non-banned user. |
| `ERR_BANNED_GROUPMEMBER` | Indicates that the banned user is trying to access the group features. |
| `ERR_ALREADY_BANNED` | Indicates that the API is trying to ban an already banned user. |
| `ERR_MEMBER_BAN_FAILED` | Indicates that the API has failed to ban a user from the group. |
| `ERR_MEMBER_UNBAN_FAILED` | Indicates that the API has failed to unban a user for the group. |
| `ERR_GROUP_NO_CLEARANCE` | Indicates that the user does not have permission to perform the action in the group.
For example, user with participant scope can not kick users with admin or moderator scope. |
| `ERR_GROUP_NO_ADMIN_SCOPE` | Indicates that the user does not have admin scope in the group. |
| `ERR_GROUP_NO_MODERATOR_SCOPE` | Indicates that the user does not have moderator scope in the group. |
| `ERR_GROUP_NO_SCOPE_CLEARANCE` | Indicates that the user does not have permission to change scope of other user. |
| `ERR_GROUP_NO_SELF_ACTION` | Indicates that the user is not allowed to perform action on himself.
For example, changing his own scope. |
| **Message Errors** | |
| `ERR_EMPTY_RECEIVER` | Indicates that the receiver cannot be empty. |
| `ERR_INVALID_RECEIVER_TYPE` | Indicates that the invalid receiver type. |
| `ERR_CONVERSATION_NOT_FOUND` | Indicates that the conversation id does not exists. |
| `ERR_CONVERSATION_NOT_ACCESSIBLE` | Indicates that the conversation id not accessible to the user.
1. A user can access his own one-to-one conversations.
2. A user can access the group conversations if he is member of the group. |
| `ERR_USER_MESSAGE_DELETE_FAILED` | Indicates that the API has failed to delete a one-to-one message. |
| `ERR_MESSAGE_ID_NOT_FOUND` | Indicates that the message does not exist. |
| `ERR_INVALID_MESSAGE_DATA` | Indicates invalid message body. |
| `ERR_EMPTY_MESSAGE_TEXT` | Indicates empty messages text for a text message. |
| `ERR_INVALID_MESSAGE_TEXT` | Indicates that the message text should be string. |
| `ERR_EMPTY_MESSAGE_CATEGORY` | Indicates message category cannot be empty. |
| `ERR_INVALID_MESSAGE_CATEGORY` | Indicates invalid message category. |
| `ERR_EMPTY_MESSAGE_TYPE` | Indicates message type cannot be empty. |
| `ERR_INVALID_MESSAGE_TYPE` | Indicates invalid message type. |
| `ERR_EMPTY_MESSAGE_FILE` | Indicates empty FILE for the media message. |
| `ERR_MESSAGE_NOT_A_SENDER` | Indicates that only sender can edit/delete the message. |
| `ERR_MESSAGE_NO_ACCESS` | Indicates user does not have access to the message.
1. For one-to-one message user should either be sender or receiver of the message.
2. For group message user should be the member of the group. |
| `ERR_MESSAGE_ACTION_NOT_ALLOWED` | Indicates that the message can not be edited or deleted.
For example, Action messages cannot be edited or deleted by the API. |
| `ERR_EMPTY_CUSTOM_DATA` | Indicates `data.customData` can not be empty for custom message. |
| `ERR_INVALID_MEDIA_MESSAGE` | Indicates invalid media message. |
| `ERR_INVALID_CUSTOM_DATA` | Indicates invalid data.customData. The customData should be valid JSON. |
| `ERR_INVALID_METADATA` | Indicates invalid data.metadata. The metadata should be valid JSON. |
| `ERR_WRONG_MESSAGE_THREAD` | Indicates conversation mismatch for parent and a new threaded message. |
| `ERR_MESSAGE_THREAD_NESTING` | Indicates nested message threading. |
| `ERR_WRONG_MESSAGE_THREAD_CATEGORY` | Indicates conversation mismatch for parent and a new threaded message. |
| **Calling Errors** | |
| `ERR_CALLING_SELF` | Indicates user is initiating call with himself. |
| `ERR_CALL_BUSY_SELF` | Indicates initiator of the call is participant of another ongoing call. |
| `ERR_CALL_BUSY_GROUP` | Indicates that for a group call, the group has and existing ongoing call. |
| `ERR_CALL_BUSY_USER` | Indicates that the recipient of the call is already busy on another call. |
| `ERR_EMPTY_CALL_SESSION_ID` | Indicates empty session id. |
| `ERR_CALL_SESSION_NOT_FOUND` | Indicates that the call does not exist. |
| `ERR_CALL_TERMINATED` | Indicates that a call is terminated.
The error response is generated when a user tries to update the status of an ended call. |
| `ERR_CALL_GROUP_ALREADY_JOINED` | Indicates that the user is already a member of the group call. |
| `ERR_CALL_GROUP_ALREADY_LEFT` | Indicates that the user trying to leave the group call has already left the call. |
| `ERR_CALL_INVALID_INIT` | Indicates that call status cannot be updated to `initiated`. |
| `ERR_CALL_USER_ALREADY_JOINED` | Indicates that the one-to-one call was already joined by the recipient of the call. |
| `ERR_CALL_GROUP_INVALID_STATUS` | Indicates invalid call status for a group call.
For example, group call cannot have a busy status. |
| `ERR_CALL_ONGOING_TO_INVALID` | Indicates updating invalid status for an ongoing call.
For example, ongoing call can not become a busy call. |
| `ERR_CALL_NOT_A_PART` | Indicates that the user is not part of the call.
For example, a third user tries to join a one-to-one call. |
| `ERR_CALL_EMPTY_JOINED_AT` | Indicates that the `joinedAt` body param is required to join a group. |
| `ERR_CALL_NOT_STARTED` | Indicates that status of call cannot be changed from initiated to ended directly. |
| **Friends Errors** | |
| `ERR_ALREADY_FRIEND` | Indicates that the users are already friends. |
| `ERR_NOT_A_FRIEND` | Indicates unfriending non-friended users. |
| `ERR_CANNOT_FORM_SELF_RELATION` | Indicates user cannot friend himself. |
| `ERR_FAILED_TO_ADD_FRIEND` | Indicates that the API has failed to add friend. |
| **Block Users Errors** | |
| `ERR_CANNOT_BLOCK_SELF` | Indicates that user cannot block himself. |
| `ERR_BLOCKED_RECEIVER` | Indicates user has blocked the receiver of the message/call. |
| `ERR_BLOCKED_SENDER` | Indicates that the iniator of the call is blocked by the recipient. |
| **Extension Errors** | |
| `ERR_EXTENSION_NOT_FOUND` | Indicates extension does not exist. |
| `ERR_BLOCKED_BY_EXTENSION` | Indicates that the message is blocked by the extension.
For example, human moderation extension can block the message sending. |
| **Webhook Errors** | |
| `ERR_WEBHOOK_NOT_FOUND` | Indicates that the webhook does not exist. |
| `ERR_BLOCKED_BY_WEBHOOK` | Indicates that the message is blocked by the extension. |
| `ERR_TRIGGER_NOT_FOUND` | Indicates trigger does not exist. |
| **General Errors** | |
| `ERR_INVALID_API_VERSION` | Indicates invalid API version. |
| `ERR_API_NOT_FOUND` | Indicates one from the list below:
1. API endpoint does not exist.
2. The endpoint does not use HTTP request method using which API is called. |
| `ERR_MISSION_FAILED` | Indicates one from the list below:
1. Fatal error.
2. Database Connection Timeout. |
| `ERR_BAD_REQUEST` | Indicates the failed validations for the body params. |
| `ERR_OPERATION_FAILED` | Indicates database operation failure. |
| `ERR_EXCEPTION` | Indicates incorrectly/poorly handled exception. |
| `ERR_TOO_MANY_REQUESTS` | Indicates rate limiting. |
| `ERR_BAD_ERROR_RESPONSE` | Indicates one from the list below:
1. The API developer has used unknown error code.
2. The API developer hasn't reassigned the error code. |
| **Websocket Errors** | |
| `ERR_WS_INIT_FAILED` | Indicates failure at Web Socket Server. |
| `ERR_WS_APP_INIT_FAILED` | Indicates App creation failure at Web Socket Server. |
| `ERR_WS_APP_DESTROY_FAILED` | Indicates App delete failure at Web Socket Server. |
| `ERR_WS_ROLE_CREATION_FAILED` | Indicates role creation failure at Web Socket Server. |
| `ERR_WS_ROLE_DELETION_FAILED` | Indicates role deletion failure at Web Socket Server. |
| `ERR_WS_USER_CREATION_FAILED` | Indicates user creation failure at Web Socket Server. |
| `ERR_WS_USER_UPDATION_FAILED` | Indicates user updation failure at Web Socket Server. |
| `ERR_WS_GROUP_CREATION_FAILED` | Indicates group creation failure at Web Socket Server. |
| `ERR_WS_GROUP_DELETION_FAILED` | Indicates group deletion failure at Web Socket Server. |
| `ERR_WS_GROUP_JOIN_FAILED` | Indicates group member join failure at Web Socket Server. |