[Solved] You wrote this in application.properties:server.port: 9090Why does the server still start on port 8080? | Spring Boot

Spring Boot - Application Configuration

You wrote this in application.properties:

server.port: 9090

Why does the server still start on port 8080?

ABecause 9090 is reserved and ignored by Spring Boot

BBecause colon syntax is invalid in properties files, so property is ignored

CBecause server.port must be set in YAML only

DBecause the file name is incorrect

Step-by-Step Solution

Solution:

Step 1: Check properties file syntax
Properties files require key=value syntax. Using colon instead of equals causes the line to be ignored.
Step 2: Understand default behavior
Since the property is ignored, Spring Boot uses the default port 8080.
Final Answer:
Because colon syntax is invalid in properties files, so property is ignored -> Option B
Quick Check:
Properties syntax error = property ignored, default used [OK]

Quick Trick: Use '=' in properties files, not ':' [OK]

Common Mistakes:

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