When your Roblox game breaks, the output window is the first place to look. Error logs tell you exactly what went wrong and where. If you are seeing references to "395" in your script logs, understanding the context is the only way to fix it. That number could be a line number, a custom error code from a module, or part of a network response. Reading the log correctly saves you from guessing and helps you repair your Lua code faster.

What does 395 mean in my error log?

Roblox does not use 395 as a standard engine error code. In most cases, when you see this number, it refers to the line number in your script where the problem occurred. Look at the format of the message. If the log reads something like Workspace.Script:395: attempt to call a nil value, the issue is on line 395 of that script. Open the script editor, go to line 395, and check the code there.

If the number appears inside a custom error message, such as Error 395: Invalid data, then a module or plugin you are using defined that code. Check the documentation for any third-party tools in your game to see what their custom codes mean. Once you identify the source, you can adjust your code to match the expected input. Our notes on script optimization for beginners explain how organizing your functions reduces the chance of nil references and scope errors that often trigger these log entries.

How do I read the stack trace to find the bug?

The output window provides a stack trace that shows the path your code took before crashing. This trace lists every function call leading up to the error. Click the blue link in the output window to jump directly to the problematic line in the script editor. This link is the fastest way to locate the issue without counting lines manually.

Check the variables on that line. Common causes include trying to access a property of an object that does not exist, calling a function that hasn't loaded yet, or using the wrong data type. If line 395 uses a variable, print that variable a few lines earlier to see if it holds the value you expect. If the error occurs in a GUI script, check your event connections. A missing connection can cause functions to fire with nil arguments. Reviewing a coding example for UI interaction helps you verify that your buttons and text labels are wired correctly.

Why does the error happen only on the server or client?

Intermittent errors often point to timing or replication problems. Your script might be trying to use an object before Roblox has finished loading it. This happens frequently with player characters or assets streamed in from the server. If line 395 accesses a part or a tool, add a check to wait for the object using WaitForChild instead of assuming it is already there.

Network lag can also trigger errors in remote events. If a client fires a remote event too quickly, the server might receive data in an unexpected state. Test your game in Roblox Studio using the server-client view to see if the error appears on the server, the client, or both. Errors often surface when different game systems interact. If your script handles player stats or inventory, ensure your logic accounts for edge cases. Guidance on gameplay mechanics for Lua shows how to validate player data before processing changes, which stops many runtime errors.

How can I prevent these errors in future scripts?

Start by isolating the code around the error line. Comment out sections of the function to see which part triggers the crash. Use print() statements to display variable values right before the error. This confirms whether your objects and data are valid. For more complex issues, use the Roblox Debugger. Set a breakpoint on the line causing the error and run the game. The debugger pauses execution so you can inspect every variable in the current scope.

Heavy loops or memory leaks can cause scripts to behave unpredictably and generate confusing log entries. Learning advanced performance scripting techniques allows you to manage resources better and avoid errors related to script timeouts or memory limits. Another common mistake is ignoring yellow warnings. Warnings do not stop your script, but they can lead to errors later. If you see warnings about deprecated functions or infinite yields, address them before they cause a crash.

For official details on using the output window and debugger, refer to the Roblox Creator Documentation on debugging tools.

Quick debugging checklist

  • Check if 395 is a line number or part of a custom message.
  • Click the blue link in the output window to jump to the script.
  • Inspect variables on the error line using print statements or the debugger.
  • Look for nil values, missing objects, or typos in function names.
  • Test in server-client mode to rule out replication issues.
  • Fix any yellow warnings that appear before the error.

Keep your output window open while you test. Fixing errors as soon as they appear keeps your project stable and makes development smoother.