FIXMsgType 35=A

Logon (35=A)

FIX 4.4 Gateway TLS/TCP

The client sends Logon (35=A) to the server over TLS/TCP at fix.bitgo.com:5100 (or test). This is not an HTTP request.

Required before order entry or market-data application messages on a new session. One active order-entry session per Go Account (56=BITGO); market data uses a separate session (56=BITGO-MD).

SenderCompID (49) identifies the account; there is no separate Username (tag 553). Your access token goes in Password (554).

On success: server echoes Logon (35=A).

On failure: server sends Logout (35=5) with Text (58) describing the reason. The session does not reach the logged-on state. Common rejection texts:

Text (tag 58)	Cause
`invalid access token`	Token malformed, expired at Logon, or otherwise invalid
`missing or empty access token (tag 554)`	Tag 554 absent or empty
`invalid Go Account ID in TargetCompID: expected 32 hex chars`	Bad account ID format (swapped CompIDs)
`unknown SenderCompID: expected BITGO or BITGO-MD`	Wrong session type in tag 56 (or swapped 49/56)
`token missing trade_fix scope`	Token lacks FIX permission
`not authorised for this account`	No spend permission on the account
`rate limit exceeded on logon, retry shortly`	More than 10 Logon attempts per minute
`authentication failed`	Generic auth failure
`access token expired`	Token already expired at Logon
`active session exists for this account`	Another FIX session is already active for this account
`session enforcement failed`	Session store could not claim the account slot
`server shutting down, please reconnect`	Acceptor is draining / shutting down

Mid-session token expiry and revocation use Logout (35=5) with session expired / access token revoked (see Logout page), not these Logon reject texts.

Message fields

Tag	Field	Required	Description
554	Password	Required	Required. BitGo access token.
98	EncryptMethod	Required	Required. Must be `0` (None). TLS encrypts the transport.
108	HeartBtInt	Required	Required. Heartbeat interval in seconds. Must be `30` to match the server.
141	ResetSeqNumFlag	Optional	Optional. Must be `Y` when sent. Sequence numbers reset to 1 on every connection (stateless session model) regardless, as the server is configured with ResetOnLogon=Y.

Response messages

On success
Session established. Server echoes Logon (35=A).
On reject
Logout (35=5) with rejection reason in tag 58.

Examples

Example (pipe-delimited FIX):

8=FIX.4.4|9=128|35=A|49=0123456789abcdef0123456789abcdef|56=BITGO|34=1|554=v2_your_access_token_here|141=Y|98=0|108=30|52=20260415-14:30:00.000|10=XXX|