Fix: PostgreSQL Connection Refused – Could Not Connect to Server
How to fix the PostgreSQL error 'could not connect to server: Connection refused' caused by server not running, wrong host/port, pg_hba.conf, or firewall issues.
Tag: database
9 articles
Fix: MySQL Too Many Connections – Error 1040
How to fix the MySQL error 1040 'Too many connections' by adjusting max_connections, fixing connection leaks, and optimizing connection pooling.
Fix: PostgreSQL ERROR: duplicate key value violates unique constraint
How to fix 'duplicate key value violates unique constraint' in PostgreSQL by resetting sequences, using upserts, fixing bulk imports, and handling concurrent inserts.
Fix: django.db.utils.OperationalError: no such table (SQLite / PostgreSQL / MySQL)
How to fix Django's 'OperationalError: no such table' error caused by missing migrations, wrong database configuration, corrupted files, or Docker volume issues.
Fix: MySQL ERROR 2002 (HY000): Can't connect to local MySQL server through socket
How to fix MySQL ERROR 2002 (HY000) when the MySQL client can't connect through the Unix socket file on Linux, macOS, Docker, and WSL.
Fix: MongoServerError: bad auth / MongoNetworkError: connect ECONNREFUSED / MongooseServerSelectionError
How to fix MongoDB 'MongoServerError: bad auth Authentication failed', 'MongoNetworkError: connect ECONNREFUSED 127.0.0.1:27017', and 'MongooseServerSelectionError' connection errors. Covers MongoDB not running, connection string format, Atlas network access, Docker networking, authentication, DNS/SRV issues, TLS/SSL, and Mongoose options.
Fix: WRONGTYPE Operation against a key holding the wrong kind of value (Redis)
How to fix Redis errors: WRONGTYPE Operation against a key holding the wrong kind of value, MISCONF Redis is configured to save RDB snapshots, OOM command not allowed, READONLY You can't write against a read only replica, and other common Redis errors. Covers key type mismatches, disk issues, memory limits, eviction policies, connection problems, and serialization.
Fix: Access denied for user 'root'@'localhost' (MySQL ERROR 1045)
How to fix MySQL 'ERROR 1045 (28000): Access denied for user root@localhost (using password: YES/NO)' on Linux, macOS, Windows, and Docker. Covers password reset, auth plugin issues, skip-grant-tables recovery, MySQL 8 vs 5.7 differences, and host mismatches.
Fix: psql: error: connection to server refused (PostgreSQL)
How to fix 'could not connect to server: Connection refused', 'psql: error: connection to server at localhost port 5432 failed', and other PostgreSQL connection refused errors on Linux, macOS, Windows, and Docker.