I've just updated my discord.js from v13 to v14 and there are many errors.
Errors with message and interaction events:
Neither message nor interaction events fire.
Errors with intents:
const client = new Client({
  intents: [
    Intents.FLAGS.GUILDS,
    Intents.FLAGS.GUILD_MESSAGES,
    Intents.FLAGS.GUILD_MESSAGE_REACTIONS,
  ],
});
//     Intents.FLAGS.GUILDS,
//            ^
//
// TypeError: Cannot read properties of undefined (reading 'FLAGS')
const client = new Client({
  intents: ['GUILDS', 'GUILD_MEMBERS', 'GUILD_MESSAGES'],
});
//    throw new RangeError(ErrorCodes.BitFieldInvalid, bit);
//
// RangeError [BitFieldInvalid]: Invalid bitfield flag or number: GUILDS.
Errors with interactions:
if (interaction.isCommand()) {}
// TypeError: interaction.isCommand is not a function
if (interaction.isAutocomplete()) {}
// TypeError: interaction.isAutocomplete is not a function
if (interaction.isMessageComponent()) {}
// TypeError: interaction.isMessageComponent is not a function
if (interaction.isModalSubmit()) {}
// TypeError: interaction.isModalSubmit is not a function
Errors with channels:
if (message.channel.isText()) {}
// TypeError: channel.isText is not a function
if (message.channel.isVoice()) {}
// TypeError: channel.isVoice is not a function
if (message.channel.isDM()) {}
// TypeError: channel.isDM is not a function
if (message.channel.isCategory()) {}
// TypeError: channel.isCategory is not a function
Errors with builders and embeds:
const embed = new MessageEmbed();
//  const embed = new MessageEmbed();
//                ^
//
// TypeError: MessageEmbed is not a constructor
const button = new MessageButton();
//  const button = new MessageButton();
//                 ^
//
// TypeError: MessageButton is not a constructor
const actionRow = new MessageActionRow();
//  const actionRow = new MessageActionRow();
//                    ^
//
// TypeError: MessageActionRow is not a constructor
const selectMenu = new MessageSelectMenu();
//  const selectMenu = new MessageSelectMenu();
//                     ^
//
// TypeError: MessageSelectMenu is not a constructor
const textInput = new TextInputComponent();
//  const textInput = new TextInputComponent();
//                    ^
//
// TypeError: TextInputComponent is not a constructor
const modal = new Modal();
//  const modal = new Modal();
//                ^
//
// TypeError: Modal is not a constructor
const attachment = new MessageAttachment();
//  const attachment = new MessageAttachment();
//                     ^
//
// TypeError: MessageAttachment is not a constructor
Errors with enums:
new ButtonBuilder()
  .setCustomId('verification')
  .setStyle('PRIMARY')
// UnknownEnumValueError: Expected the value to be one of the following enum values:
//     at NativeEnumValidator.handle
new TextInputBuilder()
  .setCustomId('verification')
  .setStyle('SHORT')
// UnknownEnumValueError: Expected the value to be one of the following enum values:
//     at NativeEnumValidator.handle
