SessionRejectReason (FIX tag 373)

intFIX 4.4FIX 4.2

SessionRejectReason (tag 373) is an int field defined in FIX 4.4 and FIX 4.2. It appears in 1 message type, always optionally. It is an enumerated field with 19 defined values.

At a glance

Tag: 373
Name: SessionRejectReason
Datatype: int
Dialects: FIX 4.4 and FIX 4.2
Messages: 1
Valid values: 19

What the specification says

FIX 4.4

Code to identify reason for a session-level Reject message

FIX 4.2

Code to identify reason for a session-level Reject message.

Descriptions are quoted from the FIX Orchestra sources under the Apache 2.0 licence.

A real message using tag 373

Reject · FIX 4.4

Tag	Field	Wire value	Meaning
8	BeginString	FIX.4.4
9	BodyLength	74
35	MsgType	3	Reject
49	SenderCompID	BOARTEAM
56	TargetCompID	COUNTERPARTY
34	MsgSeqNum	2
52	SendingTime	20240101-12:00:00.000
45	RefSeqNum	1
373	SessionRejectReason	0	Invalid tag number
10	CheckSum	150

Edit and decode it yourself

Shown with | separators for readability. On the wire FIX uses SOH (0x01), an invisible control byte — and because BodyLength and CheckSum are computed over the actual bytes, the two forms have different checksums. Both are valid and both decode here.

Open in the full decoder →

Generated from the FIX 4.4 dictionary and verified at build time: it parses and validates with no issues. Open the decoder to try your own message.

Valid values

A value outside this list is not a parse error — the message still decodes — but validate() reports it as validate/value-not-in-enum.

Value	Meaning	Symbolic name	Dialects
0	Invalid tag number	INVALID_TAG_NUMBER / InvalidTagNumber	FIX 4.4, FIX 4.2
1	Required tag missing	REQUIRED_TAG_MISSING / RequiredTagMissing	FIX 4.4, FIX 4.2
2	Tag not defined for this message type	TAG_NOT_DEFINED_FOR_THIS_MESSAGE_TYPE / TagNotDefinedForThisMessageType	FIX 4.4, FIX 4.2
3	Undefined Tag	UNDEFINED_TAG / UndefinedTag	FIX 4.4, FIX 4.2
4	Tag specified without a value	TAG_SPECIFIED_WITHOUT_A_VALUE / TagSpecifiedWithoutAValue	FIX 4.4, FIX 4.2
5	Value is incorrect (out of range) for this tag	VALUE_IS_INCORRECT / ValueIsIncorrect	FIX 4.4, FIX 4.2
6	Incorrect data format for value	INCORRECT_DATA_FORMAT_FOR_VALUE / IncorrectDataFormatForValue	FIX 4.4, FIX 4.2
7	Decryption problem	DECRYPTION_PROBLEM / DecryptionProblem	FIX 4.4, FIX 4.2
8	Signature problem	SIGNATURE_PROBLEM / SignatureProblem	FIX 4.4, FIX 4.2
9	CompID problem	COMPID_PROBLEM / CompIDProblem	FIX 4.4, FIX 4.2
10	SendingTime accuracy problem	SENDINGTIME_ACCURACY_PROBLEM / SendingTimeAccuracyProblem	FIX 4.4, FIX 4.2
11	Invalid MsgType	INVALID_MSGTYPE / InvalidMsgType	FIX 4.4, FIX 4.2
12	XML Validation error	XML_VALIDATION_ERROR	FIX 4.4
13	Tag appears more than once	TAG_APPEARS_MORE_THAN_ONCE	FIX 4.4
14	Tag specified out of required order	TAG_SPECIFIED_OUT_OF_REQUIRED_ORDER	FIX 4.4
15	Repeating group fields out of order	REPEATING_GROUP_FIELDS_OUT_OF_ORDER	FIX 4.4
16	Incorrect NumInGroup count for repeating group	INCORRECT_NUMINGROUP_COUNT_FOR_REPEATING_GROUP	FIX 4.4
17	Non "data" value includes field delimiter (SOH character)	NON_DATA_VALUE_INCLUDES_FIELD_DELIMITER	FIX 4.4
99	Other	OTHER	FIX 4.4

Where tag 373 appears

Requiredness is a property of the message, not of the field: the same tag can be optional in one message and conditionally required in another.

Message	MsgType	FIX 4.4	FIX 4.2	Where in the message
Reject	3	Optional	Optional	directly on the message body

Wire format

A whole number, optionally signed. Leading zeros are legal on the wire and are preserved in the raw value. @boarteam/fix parses the value as a number and reports parse/invalid-int when it does not lex as one; the raw string is kept either way.

Read tag 373 in TypeScript

decode.tsts

import { createFixEngine } from "@boarteam/fix";import { dictionary } from "@boarteam/fix-dict-fix44";const fix = createFixEngine(dictionary);const { message, issues } = fix.parse(raw);const sessionRejectReason = message.fields[373]?.raw;// e.g. "0" — Invalid tag number// The dictionary also carries the labels:const label = fix.dictionary  .fieldByTag(373)  ?.enumValues?.find((e) => e.value === sessionRejectReason)  ?.description;

Decode this in your own code

The same engine that produced the decoded example above is an Apache-2.0 npm package with zero runtime dependencies. It runs in Node and in the browser, and parse() returns problems as data instead of throwing.

npm i @boarteam/fix @boarteam/fix-dict-fix44

Try the decoder Source on GitHub