|REBOL 3 Docs||Guide||Concepts||Functions||Datatypes||Errors|
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There are several types of errors within REBOL. When an error occurs a message is displayed that tells you what the error was and approximately where it occurred. For instance if you type:
abc ** Script Error: abc has no value. ** Where: abc
The type of error is indicated by the first few words of the message. In the above example, the error is a Script Error. Script errors are the most common and occur when you use a function of the language in the wrong way or with improper arguments. Other types of errors are described in [bad-link:concepts/error.txt] Types.
|Syntax errors||Occur when the script contains an invalid value or a missing header, quote, bracket, or parenthesis.|
|Math errors||Occur when dividing a number by zero or there was a math overflow or underflow.|
|Access errors||Occur when a file, directory, or network operation cannot be accessed or access permissions are restricted.|
|Throw errors||Occur when a break, exit, or throw is used in an improper manner.|
|User errors||Defined by the user's script.|
|Internal errors||Returned when a problem occurs within the REBOL system. If you encounter one of these types of errors, please report it to [bad-link:concepts/feedback.txt].|
Most types of errors can be trapped and processed by your script. See [bad-link:concepts/trying.txt] Blocks for a description of the try function.
When errors are encountered in non-interactive sessions, such as when running in CGI mode (-c or --cgi ) or in no window mode (-w or --nowindow ), the session is automatically terminated.
If a script terminates while running in non-interactive mode, you can use shell redirection to output the error to a file:
REBOL -cs my_script.r >> my_script.log
This appends the output to the file in most operating systems.
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