How do I fix compiler errors?

Assets/Standard Assets/Image Effects (Pro Only)/AntialiasingAsPostEffect.js(18,40): BCE0018: The name ‘PostEffectsBase’ does not denote a valid type (‘not found’).

Assets/Standard Assets/Image Effects (Pro Only)/BloomAndLensFlares.js(30,34): BCE0018: The name ‘PostEffectsBase’ does not denote a valid type (‘not found’).

Assets/Standard Assets/Image Effects (Pro Only)/ContrastEnhance.js(8,31): BCE0018: The name ‘PostEffectsBase’ does not denote a valid type (‘not found’).

The game was running just fine. I don’t know what happened. I’m extremely new to Unity.

Found a fix, just remove the folders if its giving error, everything works perfectly fine after that. Running Unity 3D 4.5.0f6

Here’s how to read the error. The first half tells you where the problem is.

Assets/Standard Assets/Image Effects(Pro Only)/AntialiasingAsPostEffect.js(18,40)

Says that the error is in the file, AntialiasingAsPostEffects.js (which is in Assets/Standard Assets/Image Effects(Pro Only)/)

The (18,40) says that line 18 of the file, column 40 is where the actual error exists.

Then,

BCE0018:The name ‘PostEffectsBase’ does not denote a valid type (‘not found’).

is your actual error message, which says you’re using something called PostEffectsBase as a type but it isn’t. That script probably has a line like PostEffectsBase _base = //something.

Since it’s a standard asset, there’s a strong chance you didn’t write that script. There’s also a strong chance that a Standard Asset isn’t broken (although it has happened before.)

With that said, it looks like you’re using a Pro Only standard asset, without having Pro installed. Without Unity Pro, there’s probably no such type as PostEffectsBase

The solution is to either buy Pro or remove the Pro Only standard asset from your project.

namespace UnityStandardAssets.ImageEffects
change to
namespace UnitySampleAssets.ImageEffects
This works on me.
If not , find the file of PostEffectsBase, check which file it used the namespace.
and you change your name ‘PostEffectsBase’ does not denote a valid type (‘not found’) code file namespace same with that PostEffectsbase file.
Because the class(file) inheritance to another class(file), you have in your folder, but some reason the error was coming.

thanks.