Application not found

You may be getting this error when trying to start a steam:// URL because of a faulty registry. This problem may occur if you transfer Steam to a different drive/directory.

To repair it, you should change the value of HKEY_CLASSES_ROOT\steam\Shell\Open\Command so it matches to that of the new drive/directory.

Example

If your old steam directory was: C:\games\Steam. Then the value of the key should look like this:

"C:\games\Steam\steam.exe" "%1"

And now you've moved it to D:\games\Steam. The new key value should look like this:

"D:\games\Steam\steam.exe" "%1"