GenerateMySqlErrorCode.cs

async Task Main()
{
	var httpClient = new HttpClient();
	var html57 = await (await httpClient.GetAsync("https://dev.mysql.com/doc/mysql-errors/5.7/en/server-error-reference.html")).Content.ReadAsStringAsync();
	var html8 = await (await httpClient.GetAsync("https://dev.mysql.com/doc/mysql-errors/8.0/en/server-error-reference.html")).Content.ReadAsStringAsync();

	var valueNames = new Dictionary<int, string>();
	foreach (MySqlErrorCode value in Enum.GetValues(typeof(MySqlErrorCode)))
	{
		var intValue = (int)value;
		valueNames[(int)value] = value.ToString();
	}

	var allErrors = new Dictionary<int, (string Name, string Description)>();
	ReadErrorsFromHtml(allErrors, valueNames, html57);
	ReadErrorsFromHtml(allErrors, valueNames, html8);

	const string fileName = @"MySqlErrorCode.g.cs";

	using (var writer = new StreamWriter(fileName))
	{
		writer.WriteLine(@"namespace MySqlConnector;

/// <summary>
/// MySQL Server error codes. Taken from <a href=""https://dev.mysql.com/doc/mysql-errors/8.0/en/server-error-reference.html"">Server Error Codes and Messages</a>.
/// </summary>
[System.CodeDom.Compiler.GeneratedCode(""https://gist.github.com/bgrainger/791cecb647d514a9dd2f3d83b2387e49"", ""5"")]
public enum MySqlErrorCode
{
	DelimiterNotSupported = -3,

	/// <summary>
	/// Not all rows from the source supplied to <see cref=""MySqlBulkCopy""/> were copied to <see cref=""MySqlBulkCopy.DestinationTableName""/>.
	/// </summary>
	BulkCopyFailed = -2,

	/// <summary>
	/// The timeout period specified by <see cref=""MySqlCommand.CommandTimeout""/> elapsed before the operation completed.
	/// </summary>
	CommandTimeoutExpired = -1,");

		foreach (var kvp in allErrors.OrderBy(x => x.Key))
		{
			writer.WriteLine();
			writer.Write($@"	/// <summary>
	/// {kvp.Value.Description}
	/// </summary>
	{kvp.Value.Name} = {kvp.Key},
");
		}

		writer.WriteLine(@"}");
	}

	File.WriteAllBytes(fileName, File.ReadAllBytes(fileName).Where(x => x != 0x0D).ToArray());
}

void ReadErrorsFromHtml(Dictionary<int, (string, string)> allErrors, Dictionary<int, string> valueNames, string html)
{
	var messageOverrides = new Dictionary<int, string>
	{
		{ 1064, "You have an error in your SQL syntax" },
		{ 1317, "Query execution was interrupted" },
	};

	var seenErrors = new HashSet<int>();

	using (var reader = new StringReader(html))
	{
		int errorCode = 0;
		string errorName = null;
		string errorMessage = null;
		string line;
		while ((line = reader.ReadLine()) != null)
		{
			if (errorName != null)
			{
				if (line.StartsWith("    </p>", StringComparison.OrdinalIgnoreCase))
				{
					if (errorMessage != null)
					{
						if (seenErrors.Add(errorCode))
						{
							errorMessage = Regex.Replace(errorMessage, @"\s+", " ").Replace(" Message: ", "");

							// try to match official name if known
							if (!valueNames.TryGetValue(errorCode, out var valueName))
							{
								// otherwise synthesise a name by CamelCasing the error code
								valueName = Regex.Replace(errorName, @"^(WARN|ER)_", "_") + "_";
								valueName = Regex.Replace(valueName, @"(?<!_)[A-Z]", x => x.Groups[0].Value.ToLowerInvariant());

								// replace some error code abbreviations with spelled-out words for the enum value name
								valueName = valueName.Replace("Cant_", "Cannot_");
								valueName = valueName.Replace("Cond_Item_", "ConditionItem_");
								valueName = valueName.Replace("Dup_", "Duplicate_");
								valueName = valueName.Replace("Fk_", "ForeignKey_");
								valueName = valueName.Replace("Ft_", "FullText_");
								valueName = valueName.Replace("Jt_", "JsonTable_");
								valueName = valueName.Replace("Tf_", "TableFunction_");
								valueName = valueName.Replace("Io_", "IO_");
								valueName = valueName.Replace("Serverid_", "ServerId_");
								valueName = valueName.Replace("Stmt_", "Statement_");
								valueName = valueName.Replace("Vcpu_", "VCpu_");
								valueName = valueName.Replace("_", "");
							}

							// NOTE: 'errorMessage' contains a human-readable error message, but it was not authored by us; use a simple description for the comment instead.
							string description;
							if (messageOverrides.TryGetValue(errorCode, out var messageOverride))
								description = $"{messageOverride} ({errorName}).";
							else
								description = errorName;

							if (!allErrors.ContainsKey(errorCode))
								allErrors.Add(errorCode, (valueName, description));
						}

						errorCode = 0;
						errorName = null;
						errorMessage = null;
					}
				}
				else
				{
					errorMessage = errorMessage + line;
				}
			}
			else
			{
				Match match;
				if ((match = Regex.Match(line, @"Error number: <code class=""literal"">([0-9]+)</code>; Symbol:")).Success)
				{
					errorCode = int.Parse(match.Groups[1].Value);
					errorName = errorMessage = null;
				}
				else if ((match = Regex.Match(line, @"<a class=""link"" href=""server-error-reference.html#[^""]+""><code class=""literal"">(.*?)</code></a>")).Success)
				{
					errorName = match.Groups[1].Value;
				}
			}
		}
	}
}

@bgrainger Looks like they moved the error list to https://dev.mysql.com/doc/refman/5.7/en/server-error-reference.html