Error Codes

The table below lists the error strings that can be returned by Barracuda App Server (BAS) Lua APIs. These strings are used across multiple modules (for example network, HTTP client, file I/O, ZIP, TLS, and proxy-related APIs).

In BAS Lua code, many functions return nil/false plus an error string when an operation fails. The recommended pattern is to compare the returned error string against the values in this table and handle the cases you care about, then fall back to a generic error handler for everything else.

For Lua developers, the important part is the Lua error string (for example cannotconnect, timeout, or notfound). The underlying C constant names are included only as secondary reference information.

Examples

HTTP client: distinguish network availability from other failures

Handle the most common connectivity errors explicitly and log the returned BAS error string for everything else.

local http = require "httpc".create()
local ok, err = http:request{url = "https://x.com"}
if not ok then
   if err == "cannotresolve" or err == "cannotconnect" then
      print("Server is not available")
   elseif err == "timeout" then
      print("Server did not respond in time")
   else
      print("HTTP request failed, code:", err)
   end
end

Disk I/O: handle missing files cleanly

Use a specific message for expected file-system cases such as notfound, while still reporting unexpected errors.

local dio = ba.openio("disk")
local fp, err = dio:open("/tmp/myfile.txt")
if not fp then
   if err == "notfound" then
      print("Cannot find the file")
   elseif err == "noaccess" then
      print("Access denied")
   else
      print("Cannot open file, code:", err)
   end
end

Reusable helper: keep error handling consistent

For larger applications, centralize common checks so the same BAS error strings are handled consistently across modules.

local function isTransientNetworkError(err)
   return err == "cannotresolve"
       or err == "cannotconnect"
       or err == "timeout"
       or err == "socketreadfailed"
       or err == "socketwritefailed"
end

local ok, err = someOperation()
if not ok then
   if isTransientNetworkError(err) then
      print("Temporary network problem, retry later")
   else
      print("Operation failed, code:", err)
   end
end

Error Types