diff --git a/errors.go b/errors.go
index 6b6f957..79e0fec 100644
--- a/errors.go
+++ b/errors.go
@@ -117,6 +117,11 @@ var (
 	ErrWrongTypeOfContent     = NewError(400, "Bad Request: wrong type of the web page content")
 	ErrWrongURL               = NewError(400, "Bad Request: wrong HTTP URL specified")
 	ErrForwardMessage         = NewError(400, "Bad Request: administrators of the chat restricted message forwarding")
+	ErrAlreadyParticipant     = NewError(400, "Bad Request: USER_ALREADY_PARTICIPANT", "User is already a participant")
+	ErrChannelsTooMuch        = NewError(400, "Bad Request: CHANNELS_TOO_MUCH")
+	ErrUserChannelsTooMuch    = NewError(400, "Bad Request: USER_CHANNELS_TOO_MUCH")
+	ErrHideRequesterMissing   = NewError(400, "Bad Request: HIDE_REQUESTER_MISSING")
+	ErrUserIDInvalid          = NewError(400, "Bad Request: USER_ID_INVALID")
 )
 
 // Forbidden errors