所有由PostgreSQL伺服器回傳的訊息，都會搭配一個 5 個字元的錯誤代碼，這些代碼均以 SQL 標準的 SQLSTATE 代碼所定義。應用程式應該以錯誤代碼作為程式行為，而非處理文字的錯誤訊息。這些錯誤代碼會隨 PostgreSQL 版本發佈而微幅更新，但不會因為不同語言的文字訊息影響其定義。特別注意，部份錯誤代碼是以 SQL 標準的定義所制定，而有些錯誤代碼是額外制定的，以對應其他 SQL 標準未定義的使用情況。
標準來看，錯誤代碼的前 2 個字元代表著這個錯誤的類別，而後面 3 個字元則指出在此類別中更詳細的發生情況。所以，應用程式即使未完整支援特定的錯誤代碼，仍然可以依類別代碼瞭解大概發生了什麼事。
下方的 Table A.1 列出了所有在 PostgreSQL 10 中所定義的錯誤代碼。（部份錯誤代碼可能實際上沒有使用，但仍然依 SQL 標準所制定）每一個錯誤的類別都有一個＂標準＂的錯誤情況，其最後 3 個字元為 000，只用於在該類別未特別詳細定義的錯誤情況。
在＂Condition Name＂欄位中的內容將能在 PL/pgSQL 中被使用。Condition Name 不論大小寫字母均可合法使用。（特別注意，PL/pgSQL 並不支援 00、01 及 02 的錯誤類別。）
有一些錯誤訊息，其回傳內容是發生錯誤的資料庫物件名稱（表格 Table、表格欄位 Table column、資料型別 data type、限制條件 constraint）。舉例來說，如果產生了 unique_violation 錯誤，則會回傳某個限制條件名稱。這些訊息將會分別額外的欄位回傳，所以應用程式不需要特別解譯描述性的訊息內容。在 PostgreSQL 9.3之前，這種回傳方式僅限於 SQLSTATE 類別 23（違反限制條件的一致性 integrity constraint violation），日後將儘可能延伸支援到所有類別。
Class 00 — Successful Completion
00000
successful_completion
Class 01 — Warning
01000
warning
0100C
dynamic_result_sets_returned
01008
implicit_zero_bit_padding
01003
null_value_eliminated_in_set_function
01007
privilege_not_granted
01006
privilege_not_revoked
01004
string_data_right_truncation
01P01
deprecated_feature
Class 02 — No Data (this is also a warning class per the SQL standard)
02000
no_data
02001
no_additional_dynamic_result_sets_returned
Class 03 — SQL Statement Not Yet Complete
03000
sql_statement_not_yet_complete
Class 08 — Connection Exception
08000
connection_exception
08003
connection_does_not_exist
08006
connection_failure
08001
sqlclient_unable_to_establish_sqlconnection
08004
sqlserver_rejected_establishment_of_sqlconnection
08007
transaction_resolution_unknown
08P01
protocol_violation
Class 09 — Triggered Action Exception
09000
triggered_action_exception
Class 0A — Feature Not Supported
0A000
feature_not_supported
Class 0B — Invalid Transaction Initiation
0B000
invalid_transaction_initiation
Class 0F — Locator Exception
0F000
locator_exception
0F001
invalid_locator_specification
Class 0L — Invalid Grantor
0L000
invalid_grantor
0LP01
invalid_grant_operation
Class 0P — Invalid Role Specification
0P000
invalid_role_specification
Class 0Z — Diagnostics Exception
0Z000
diagnostics_exception
0Z002
stacked_diagnostics_accessed_without_active_handler
Class 20 — Case Not Found
20000
case_not_found
Class 21 — Cardinality Violation
21000
cardinality_violation
Class 22 — Data Exception
22000
data_exception
2202E
array_subscript_error
22021
character_not_in_repertoire
22008
datetime_field_overflow
22012
division_by_zero
22005
error_in_assignment
2200B
escape_character_conflict
22022
indicator_overflow
22015
interval_field_overflow
2201E
invalid_argument_for_logarithm
22014
invalid_argument_for_ntile_function
22016
invalid_argument_for_nth_value_function
2201F
invalid_argument_for_power_function
2201G
invalid_argument_for_width_bucket_function
22018
invalid_character_value_for_cast
22007
invalid_datetime_format
22019
invalid_escape_character
2200D
invalid_escape_octet
22025
invalid_escape_sequence
22P06
nonstandard_use_of_escape_character
22010
invalid_indicator_parameter_value
22023
invalid_parameter_value
22013
invalid_preceding_or_following_size
2201B
invalid_regular_expression
2201W
invalid_row_count_in_limit_clause
2201X
invalid_row_count_in_result_offset_clause
2202H
invalid_tablesample_argument
2202G
invalid_tablesample_repeat
22009
invalid_time_zone_displacement_value
2200C
invalid_use_of_escape_character
2200G
most_specific_type_mismatch
22004
null_value_not_allowed
22002
null_value_no_indicator_parameter
22003
numeric_value_out_of_range
2200H
sequence_generator_limit_exceeded
22026
string_data_length_mismatch
22001
string_data_right_truncation
22011
substring_error
22027
trim_error
22024
unterminated_c_string
2200F
zero_length_character_string
22P01
floating_point_exception
22P02
invalid_text_representation
22P03
invalid_binary_representation
22P04
bad_copy_file_format
22P05
untranslatable_character
2200L
not_an_xml_document
2200M
invalid_xml_document
2200N
invalid_xml_content
2200S
invalid_xml_comment
2200T
invalid_xml_processing_instruction
22030
duplicate_json_object_key_value
22031
invalid_argument_for_sql_json_datetime_function
22032
invalid_json_text
22033
invalid_sql_json_subscript
22034
more_than_one_sql_json_item
22035
no_sql_json_item
22036
non_numeric_sql_json_item
22037
non_unique_keys_in_a_json_object
22038
singleton_sql_json_item_required
22039
sql_json_array_not_found
2203A
sql_json_member_not_found
2203B
sql_json_number_not_found
2203C
sql_json_object_not_found
2203D
too_many_json_array_elements
2203E
too_many_json_object_members
2203F
sql_json_scalar_required
2203G
sql_json_item_cannot_be_cast_to_target_type
Class 23 — Integrity Constraint Violation
23000
integrity_constraint_violation
23001
restrict_violation
23502
not_null_violation
23503
foreign_key_violation
23505
unique_violation
23514
check_violation
23P01
exclusion_violation
Class 24 — Invalid Cursor State
24000
invalid_cursor_state
Class 25 — Invalid Transaction State
25000
invalid_transaction_state
25001
active_sql_transaction
25002
branch_transaction_already_active
25008
held_cursor_requires_same_isolation_level
25003
inappropriate_access_mode_for_branch_transaction
25004
inappropriate_isolation_level_for_branch_transaction
25005
no_active_sql_transaction_for_branch_transaction
25006
read_only_sql_transaction
25007
schema_and_data_statement_mixing_not_supported
25P01
no_active_sql_transaction
25P02
in_failed_sql_transaction
25P03
idle_in_transaction_session_timeout
Class 26 — Invalid SQL Statement Name
26000
invalid_sql_statement_name
Class 27 — Triggered Data Change Violation
27000
triggered_data_change_violation
Class 28 — Invalid Authorization Specification
28000
invalid_authorization_specification
28P01
invalid_password
Class 2B — Dependent Privilege Descriptors Still Exist
2B000
dependent_privilege_descriptors_still_exist
2BP01
dependent_objects_still_exist
Class 2D — Invalid Transaction Termination
2D000
invalid_transaction_termination
Class 2F — SQL Routine Exception
2F000
sql_routine_exception
2F005
function_executed_no_return_statement
2F002
modifying_sql_data_not_permitted
2F003
prohibited_sql_statement_attempted
2F004
reading_sql_data_not_permitted
Class 34 — Invalid Cursor Name
34000
invalid_cursor_name
Class 38 — External Routine Exception
38000
external_routine_exception
38001
containing_sql_not_permitted
38002
modifying_sql_data_not_permitted
38003
prohibited_sql_statement_attempted
38004
reading_sql_data_not_permitted
Class 39 — External Routine Invocation Exception
39000
external_routine_invocation_exception
39001
invalid_sqlstate_returned
39004
null_value_not_allowed
39P01
trigger_protocol_violated
39P02
srf_protocol_violated
39P03
event_trigger_protocol_violated
Class 3B — Savepoint Exception
3B000
savepoint_exception
3B001
invalid_savepoint_specification
Class 3D — Invalid Catalog Name
3D000
invalid_catalog_name
Class 3F — Invalid Schema Name
3F000
invalid_schema_name
Class 40 — Transaction Rollback
40000
transaction_rollback
40002
transaction_integrity_constraint_violation
40001
serialization_failure
40003
statement_completion_unknown
40P01
deadlock_detected
Class 42 — Syntax Error or Access Rule Violation
42000
syntax_error_or_access_rule_violation
42601
syntax_error
42501
insufficient_privilege
42846
cannot_coerce
42803
grouping_error
42P20
windowing_error
42P19
invalid_recursion
42830
invalid_foreign_key
42602
invalid_name
42622
name_too_long
42939
reserved_name
42804
datatype_mismatch
42P18
indeterminate_datatype
42P21
collation_mismatch
42P22
indeterminate_collation
42809
wrong_object_type
428C9
generated_always
42703
undefined_column
42883
undefined_function
42P01
undefined_table
42P02
undefined_parameter
42704
undefined_object
42701
duplicate_column
42P03
duplicate_cursor
42P04
duplicate_database
42723
duplicate_function
42P05
duplicate_prepared_statement
42P06
duplicate_schema
42P07
duplicate_table
42712
duplicate_alias
42710
duplicate_object
42702
ambiguous_column
42725
ambiguous_function
42P08
ambiguous_parameter
42P09
ambiguous_alias
42P10
invalid_column_reference
42611
invalid_column_definition
42P11
invalid_cursor_definition
42P12
invalid_database_definition
42P13
invalid_function_definition
42P14
invalid_prepared_statement_definition
42P15
invalid_schema_definition
42P16
invalid_table_definition
42P17
invalid_object_definition
Class 44 — WITH CHECK OPTION Violation
44000
with_check_option_violation
Class 53 — Insufficient Resources
53000
insufficient_resources
53100
disk_full
53200
out_of_memory
53300
too_many_connections
53400
configuration_limit_exceeded
Class 54 — Program Limit Exceeded
54000
program_limit_exceeded
54001
statement_too_complex
54011
too_many_columns
54023
too_many_arguments
Class 55 — Object Not In Prerequisite State
55000
object_not_in_prerequisite_state
55006
object_in_use
55P02
cant_change_runtime_param
55P03
lock_not_available
55P04
unsafe_new_enum_value_usage
Class 57 — Operator Intervention
57000
operator_intervention
57014
query_canceled
57P01
admin_shutdown
57P02
crash_shutdown
57P03
cannot_connect_now
57P04
database_dropped
57P05
idle_session_timeout
Class 58 — System Error (errors external to PostgreSQL itself)
58000
system_error
58030
io_error
58P01
undefined_file
58P02
duplicate_file
Class 72 — Snapshot Failure
72000
snapshot_too_old
Class F0 — Configuration File Error
F0000
config_file_error
F0001
lock_file_exists
Class HV — Foreign Data Wrapper Error (SQL/MED)
HV000
fdw_error
HV005
fdw_column_name_not_found
HV002
fdw_dynamic_parameter_value_needed
HV010
fdw_function_sequence_error
HV021
fdw_inconsistent_descriptor_information
HV024
fdw_invalid_attribute_value
HV007
fdw_invalid_column_name
HV008
fdw_invalid_column_number
HV004
fdw_invalid_data_type
HV006
fdw_invalid_data_type_descriptors
HV091
fdw_invalid_descriptor_field_identifier
HV00B
fdw_invalid_handle
HV00C
fdw_invalid_option_index
HV00D
fdw_invalid_option_name
HV090
fdw_invalid_string_length_or_buffer_length
HV00A
fdw_invalid_string_format
HV009
fdw_invalid_use_of_null_pointer
HV014
fdw_too_many_handles
HV001
fdw_out_of_memory
HV00P
fdw_no_schemas
HV00J
fdw_option_name_not_found
HV00K
fdw_reply_handle
HV00Q
fdw_schema_not_found
HV00R
fdw_table_not_found
HV00L
fdw_unable_to_create_execution
HV00M
fdw_unable_to_create_reply
HV00N
fdw_unable_to_establish_connection
Class P0 — PL/pgSQL Error
P0000
plpgsql_error
P0001
raise_exception
P0002
no_data_found
P0003
too_many_rows
P0004
assert_failure
Class XX — Internal Error
XX000
internal_error
XX001
data_corrupted
XX002
index_corrupted