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Symbolication Response

The response to a symbolication request is a JSON object which contains different data depending on the status of the symbolication job:

  • pending: Symbolication has not finished yet; try again later. This is only returned after the timeout has expired, if one was specified.
  • complete: The symbolication request has been processed and results are ready. This status is only reported once, after which the job is cleaned up.
  • error: Something went wrong during symbolication, and details are in the payload.

Success Response

Symbol server responds with 200 OK and the response payload listed below if symbolication succeeds within a configured timeframe (around 20 seconds):

  "status": "complete",

  // Symbolicated stack traces
  "stacktraces": [
      "frames": [
          // Symbolication meta data
          "status": "symbolicated",
          "original_index": 0,

          // Frame information
          "instruction_addr": "0xfeedbeef",  // actual address of the frame
          "addr_mode": "abs",                // address mode
          "sym_addr": "0xfeed0000",          // start address of the function
          "package": "/path/to/",   // path to the module's code file
          "symbol": "__1cGmemset6FpviI_0_",  // original mangled function name
          "function": "memset",              // demangled short version of symbol
          "lang": "cpp",
          "abs_path": "/path/to/src/file.c", // normalized absolute path
          "filename": "../src/file.c",       // path relative to compilation dir
          "lineno": 22,
      "registers": { ... }

  // Modules completed with information read from object files
  "modules": [
      "status": "found",
  // Additional information read from crash report
  "arch": "x86_64",
  "signal": 11,
  "os": {
    "name": "Windows NT",
    "version": "8.1.2700"

The symbolicated frames are returned in the same order as provided in the request. Additional properties passed in the request are discarded. Errors that occurred during symbolication, such as missing symbol files or unresolvable addresses within symbols are reported as values for status in both modules and frames.

Note on Addresses

Addresses (instruction_addr and sym_addr) can come in two versions. They can be absolute or relative. Symbolicator will always try to make addresses absolute but in some cases this cannot be done. For instance WASM modules do not have absolute addresses in which case the addresses stay relative. This is identified by the addr_mode property. When it's set to "abs" it means the addresses are absolute, when "rel:X" it's relative to module index X.

Backoff Response

If symbolication takes longer than the threshold timeout, the server instead responds with a backoff response. It will then continue to fetch symbols and symbolication. The response indicates the estimated time for symbol retrieval, after which the symbolication request can be expected to succeed:

  "status": "pending",
  "request_id": "deadbeef",
  "retry_after": 300 // 5 minutes

The symbolication server must not send a backoff response if no timeout was sent by the client.

Note that the retry_after value is just an estimation and does not give any guarantee. The request may be repeated at any time:

GET /requests/deadbeef?timeout=123

Invalid Request Response

If the user provided a non-existent request ID, the server responds with 404 Not Found.

Requests should always be treated transient as they might disappear during a deploy. Clients must expect that 404 is returned even for valid request IDs and then re-schedule symbolication

On a related note, state on the server is generally ephemeral.