Speech recognition errors can be broadly recognized as follows: FACILITY_SAPI is 0x00040000 (the same as FACILITY_ITF) and WinRT speech error codes start at 0x5500. So a code greater than or equal to 0x80045500 is an error from the speech recognition system.

Error and error code Error description
SPERR_AUDIO_LIMIT_EXCEEDED 0x8004550A The audio of a speech input attempt exceeds the supported limit.
SPERR_CANNOT_DISABLE_ROOTRULE 0x80045511 Root rule cannot be disabled.
SPERR_CANT_CHANGE_RULE_STATE 0x8004550d Rule cannot be enabled/disabled because its grammar has not been loaded.
SPERR_CANT_MODIFY_FINAL_STATE 0x8004550F Final state should not have transitions.
SPERR_GRAMMAR_DUP_NAME 0x80045505 The grammar set contains more than one grammar with the same name.
SPERR_GRAMMARSET_CANT_ADD 0x80045506 The grammar could not be added to the grammar set.
SPERR_GRAMMARSET_LOAD_CANCELED 0x80045507 An operation to load a grammar to a grammar set was cancelled.
SPERR_NO_GRAMMAR_ENABLED 0x8004550C Recognition can't be performed because no grammar is enabled
SPERR_NO_GRAMMARS_TO_SERIALIZE 0x80045512 No grammars loaded, nothing to serialize. Grammars have to be loaded before they can be serialized to a folder.
SPERR_NO_RULES_TO_ACTIVATE 0x8004550B There are no active rules in any loaded grammars.
SPERR_RECOERROR_NETWORK_TIMEOUT 0x80045503 The network connection timed out.
SPERR_RECOERROR_NETWORK_UNAVAILABLE 0x80045504 The network connection is not available.
SPERR_RECOERROR_NOMATCH 0x80045502 Speech input could not be matched to an enabled grammar.
SPERR_RECOERROR_NOSPEECH 0x80045501 No speech was detected during a recognition operation. This usually indicates that the recognition operation has timed-out before something was recognized. It is safe to ignore this error and just to start another recognition. To reduce incidence of this error, set the InitialSilenceTimeout and BabbleTimeout settings of the speech recognizer to suitably large values.
SPERR_ROOTRULE_NOT_SET 0x80045510 Root rule has not been set.
SPERR_SPEECH_PRIVACY_POLICY_NOT_ACCEPTED 0x80045509 The speech privacy policy was not accepted before the first attempt to use speech recognition on the phone.
SPERR_START_STATE_NOT_SET 0x8004550E Graph rule does not have a start state defined.
SPERR_SYSTEM_CALL_INTERRUPTED 0x80045508 A speech operation was aborted by a system call, for example fast app switching or an incoming phone call.
SPERR_UNSUPPORTED_WHEN_OUT_OF_FOCUS 0x80045513 This operation is not supported when the recognizer is out of focus.
SPERR_WINRT_ALREADY_IN_LEX 0x800455A1 The word, pronunciation, or POS pair being added is already in lexicon.
SPERR_WINRT_AMBIGUOUS_PROPERTY 0x800455AD Cannot add ambiguous property.
SPERR_WINRT_CFG_INVALID_DATA 0x800455B9 The data in the CFG grammar is invalid or corrupted.
SPERR_WINRT_CIRCULAR_REFERENCE 0x800455A7 Circular reference in import rules of grammars.
SPERR_WINRT_CIRCULAR_RULE_REF 0x800455AB Rule 'A' refers to a second rule 'B' which, in turn, refers to rule 'A'.
SPERR_WINRT_DUPLICATE_RESOURCE_NAME 0x800455A5 A resource name was duplicated for a given rule.
SPERR_WINRT_DUPLICATE_RULE_NAME 0x800455A4 A rule name was duplicated.
SPERR_WINRT_EXPORT_DYNAMIC_RULE 0x800455AE Exported rules cannot refer directly or indirectly to a dynamic rule.
SPERR_WINRT_INTERNAL_ERROR 0x800455A0 Generic error that is not actionable by developers.
SPERR_WINRT_INVALID_IMPORT 0x800455A8 A rule reference to an imported grammar that could not be resolved.
SPERR_WINRT_LANGID_MISMATCH 0x800455B1 An attempt to load a CFG grammar with a LANGID different than other loaded grammars.
SPERR_WINRT_LEX_INVALID_DATA 0x800455B8 The lexicon data is invalid or corrupted.
SPERR_WINRT_NO_MORE_ITEMS 0x800455BF When enumerating items, the requested index is greater than the count of items.
SPERR_WINRT_NO_RULES 0x800455AA A grammar contains no top-level, dynamic, or exported rules. There is no possible way to activate or otherwise use any rule in this grammar.
SPERR_WINRT_NO_RULES_TO_ACTIVATE 0x800455B7 The grammar does not have any root or top-level active rules to activate.
SPERR_WINRT_NO_WORD_PRONUNCIATION 0x800455B2 The SR engine is unable to add this word to a grammar. The application may need to supply an explicit pronunciation for this word.
SPERR_WINRT_NOT_DYNAMIC_GRAMMAR 0x800455AC Attempt was made to manipulate a non-dynamic grammar.
SPERR_WINRT_NOT_IN_LEX 0x800455A2 The word does not exist in the lexicon.
SPERR_WINRT_NOT_TOPLEVEL_RULE 0x800455C6 The rule exists but is not a top-level rule.
SPERR_WINRT_PHONEME_CONVERSION 0x800455B6 Cannot convert the phonemes to the specified phonetic alphabet.
SPERR_WINRT_ROOTRULE_ALREADY_DEFINED 0x800455B4 There is already a root rule for this grammar Defining another root rule will fail.
SPERR_WINRT_RULE_NAME_ID_CONFLICT 0x800455A9 A rule exists with matching IDs (names) but different names (IDs).
SPERR_WINRT_RULE_NOT_DYNAMIC 0x800455A3 An attempt was made to modify a non-dynamic rule.
SPERR_WINRT_RULE_NOT_FOUND 0x800455C5 Specified rule not found.
SPERR_WINRT_SISR_ATTRIBUTES_NOT_ALLOWED 0x800455BA Attributes are not allowed at the top level.
SPERR_WINRT_SISR_MIXED_NOT_ALLOWED 0x800455BB Mixed content is not allowed at the top level.
SPERR_WINRT_SML_GENERATION_FAIL 0x800455B3 The SML couldn't be generated. For example, the transformation xslt template is not well formed.
SPERR_WINRT_STATE_WITH_NO_ARCS 0x800455C4 State with no arcs or no valid path to end state.
SPERR_WINRT_STRING_EMPTY 0x800455BE The string cannot be empty.
SPERR_WINRT_STRING_TOO_LONG 0x800455BD The string is too long.
SPERR_WINRT_TOO_MANY_GRAMMARS 0x800455A6 Too many grammars have been loaded.
SPERR_WINRT_UNSUPPORTED_LANG 0x800455BC The requested language is not supported.
SPERR_WINRT_UNSUPPORTED_PHONEME 0x800455B5 Unknown phoneme.
SPERR_WINRT_WORDFORMAT_ERROR 0x800455AF Incorrect word format, probably due to incorrect pronunciation string.