Common Java Errors and How to Fix Them
Browse all documented Java errors with detailed explanations, root causes, and step-by-step fixes.
Cannot execute query with parameter types [java.util.Date, java.lang.String] in
This error occurs when trying to execute a prepared statement with parameters of unsupported types. The JDBC driver does…
java.util.ConcurrentModificationException: null at java.base/java.util.ArrayList
This error occurs when a program attempts to modify a collection (like an ArrayList or HashSet) while it is being iterat…
The SQL syntax error or exception 'ORA-01722: invalid number' occurred while exe
This error is thrown when the database encounters an invalid number while executing a SQL query. This can happen when th…
Cannot execute query: 'SELECT * FROM users WHERE id = ?': ResultSet is closed
This error occurs when you try to access a result set after it has been closed, typically after a database query.…
Uncaught java.lang.StackOverflowError: null at com.example.MyClass.myMethod(MyCl
This error occurs when a program runs out of stack space and exceeds the maximum depth of method calls, typically due to…
Cannot serialize instance of com.mysql.cj.jdbc.NonTransientConnectionException:
This error occurs when the Java application is unable to acquire a connection to the database, often due to a high load …
Syntax error on token "class", delete this token
This error occurs when the Java compiler encounters an invalid or unexpected token in the code, often due to incorrect f…
Parameter index out of range: 3, number of parameters: 2
This error occurs when a prepared statement is executed with a parameter index that does not exist in the SQL query. It …
Cannot find symbol: variable 'result' in class 'Main'
This error occurs when the Java compiler is unable to find a variable, method, or class that is being used. It's a commo…
Bean definition 'springSecurityFilterChain' could not be registered as it doesn'
This error is caused when Spring Boot is unable to register a bean due to it not implementing a valid ServiceLoader inte…
Cannot find symbol: variable 'employee' in method 'int main(java.lang.String[])'
This error occurs when Java cannot find a declared variable or method within the current scope. This can be caused by a …
Cannot convert SQL ResultSet to ArrayList of UserObject due to column name misma
This error occurs when the Java application attempts to map the result set from a database query to a custom object, but…
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