Error map
Hibernate ConstraintViolationException org.hibernate.exception.ConstraintViolationException: could not execute statement
Java · layer 4, Application & API
Centre: this error. First ring: errors it is linked with (12). Outer ring: what those are linked with. Colours show the layer of a request each error belongs to. Click any dot to re-centre the map on it; hover to follow its connections. The centre dot opens the error page.
Directly related (12)
MySQL ERROR 1062 (23000): Duplicate entry for key
An INSERT/UPDATE would create a duplicate value in a PRIMARY or UNIQUE key.
org.hibernate.LazyInitializationException: could not initialize proxy - no Session
A lazy-loaded association was accessed after the Hibernate session/transaction closed.
Performance: N+1 query problem (one query per row in a loop)
Code runs one query to load a list, then one more query per item — hundreds of queries per page.
DbUpdateException: An error occurred while saving the entity changes. See the inner exception for details.
SaveChanges failed in the database; the inner exception (SqlException/PostgresException) has the real reason — constraint violati…
IncorrectResultSizeDataAccessException: query did not return a unique result: 2
A query expected one row but found several.
sqlalchemy.exc.OperationalError: (psycopg2.OperationalError) connection to server … failed
SQLAlchemy’s DB driver raised an operational error — connection failures, lost connections or locked SQLite databases.
sqlalchemy.exc.IntegrityError: (psycopg2.errors.UniqueViolation) duplicate key value violates unique constraint
A database constraint (unique, foreign key, not null) rejected an insert/update made through SQLAlchemy.
PostgreSQL: ERROR: duplicate key value violates unique constraint
An INSERT/UPDATE would create a duplicate in a UNIQUE or PRIMARY KEY column — or the id sequence is behind the existing data.
ERROR: update or delete on table "users" violates foreign key constraint on table "orders" — Key (id)=(5) is still referenced
You tried to delete a row that other rows still reference.
API Error: Resource already exists (ALREADY_EXISTS / resource_already_exists / 409)
The create request was refused because an object with the same unique identity — name, email, external ID — already exists.
org.hibernate.TransientObjectException: object references an unsaved transient instance - save the transient instance before flushing
An entity references another entity that hasn’t been saved yet, and no cascade is configured.
MySQL ERROR 1022 (23000): Can't write; duplicate key in table
An ALTER/CREATE produced a duplicate key or constraint name — often a foreign key name that already exists in the database.
Two steps away (29)
MySQL ERROR 1452: Cannot add or update a child row: a foreign key constraint fails
You inserted/updated a row whose foreign key value doesn’t exist in the referenced parent table.
Deadlock found when trying to get lock; try restarting transaction
Two transactions waited on each other’s locks; the database killed one so the other could continue.
HTTP 409 Conflict
The request conflicts with the current state of the resource — e.g. a duplicate or an edit based on an outdated version.
com.fasterxml.jackson.databind.exc.InvalidDefinitionException: No serializer found for class X and no properties discovered
Jackson can’t serialize the class — it has no public getters/fields, or it’s a Hibernate proxy, or Java 8 date types without the…
SequelizeConnectionRefusedError: connect ECONNREFUSED 127.0.0.1:5432
Sequelize couldn’t connect to the database server.
HTTP 504 Gateway Timeout
A proxy or gateway waited too long for the upstream server to respond and gave up.
Cloudflare Error 524: A Timeout Occurred
Cloudflare connected to the origin, but the origin didn’t send an HTTP response within 100 seconds.
HTTP 304 Not Modified
The cached copy is still valid, so the server sends no body and the client reuses its cache.
JsonException: A possible object cycle was detected
System.Text.Json found a reference loop (e.g. Order → Customer → Orders → …) while serialising, usually from EF Core navigation p…
MySQL ERROR 1048 (23000): Column 'x' cannot be null
An INSERT/UPDATE put NULL into a NOT NULL column.
MySQL ERROR 1451 (23000): Cannot delete or update a parent row: a foreign key constraint fails
You tried to delete/update a row that other rows still reference.
Subquery returns more than 1 row (MySQL 1242) / more than one row returned by a subquery used as an expression
A subquery used where a single value is expected (`= (SELECT …)`) returned several rows.
MySQL ERROR 1093 (HY000): You can't specify target table 'x' for update in FROM clause
An UPDATE/DELETE uses a subquery that reads from the same table, which MySQL doesn’t allow directly.
MySQL ERROR 1175 (HY000): You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column
MySQL Workbench’s safe updates mode blocked an UPDATE/DELETE without a key-based WHERE.
MySQL ERROR 2006 (HY000): MySQL server has gone away
The connection to MySQL was closed — usually by a timeout or a packet larger than `max_allowed_packet`.
PostgreSQL: could not connect to server / connection refused — Is the server running on host and accepting TCP/IP connections?
The client reached no PostgreSQL listener at that host/port — the server is down, listening elsewhere, or not accepting remote co…
HikariPool-1 - Connection is not available, request timed out after 30000ms
The connection pool was exhausted — all connections were busy for 30 seconds.
MongoServerError: E11000 duplicate key error collection: db.users index: email_1 dup key
An insert/update violated a unique index in MongoDB.
PrismaClientKnownRequestError P2002: Unique constraint failed on the fields: (`email`)
A Prisma create/update violated a unique constraint.
ERROR: null value in column "x" of relation "y" violates not-null constraint
An INSERT/UPDATE put NULL into a NOT NULL column.
ERROR: insert or update on table "x" violates foreign key constraint "fk" — Key (user_id)=(5) is not present in table "users"
The row references a parent row that doesn’t exist.
ERROR: new row for relation "x" violates check constraint "y"
A value failed a CHECK constraint (e.g. price > 0, status IN (…)).
ERROR: there is no unique or exclusion constraint matching the ON CONFLICT specification
INSERT … ON CONFLICT (cols) names columns that don’t have a matching unique index/constraint.
sqlite3.IntegrityError: UNIQUE constraint failed: users.email
An insert/update duplicated a value in a UNIQUE or PRIMARY KEY column in SQLite.
sqlite3.IntegrityError: NOT NULL constraint failed: table.column
A NULL went into a NOT NULL column in SQLite.
SQL Server: Violation of PRIMARY KEY constraint 'x'. Cannot insert duplicate key in object 'y'. (Msg 2627)
An insert duplicated a primary key or unique constraint value.
MySQL ERROR 1146 (42S02): Table 'db.table' doesn't exist
The query references a table that MySQL can’t find in that database.
MySQL ERROR 1051 (42S02): Unknown table 'x'
DROP TABLE targeted a table that doesn’t exist.
MySQL ERROR 1060 (42S21): Duplicate column name 'x'
A CREATE/ALTER adds a column that already exists, or a SELECT in a view/derived table produces two columns with the same name.
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