Thirty Years of Backwards Compatibility

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In response to my earlier series on error handling in VBScript, Ian Griffiths blogged

that Reuben Harris noticed an interesting fact about VBScript error numbers -- a fact which I will shamelessly steal and blog about myself.

Here's the complete VBScript runtime error number table.

5 Invalid procedure call or argument
6 Overflow
7 Out of memory
9 Subscript out of range
10 This array is fixed or temporarily locked
11 Division by zero
13 Type mismatch
14 Out of string space
17 Can't perform requested operation
28 Out of stack space
35 Sub or Function not defined
48 Error in loading DLL
51 Internal error
52 Bad file name or number
53 File not found
54 Bad file mode
55 File already open
57 Device I/O error
58 File already exists
61 Disk full
62 Input past end of file
67 Too many files
68 Device unavailable
70 Permission denied
71 Disk not ready
74 Can't rename with different drive
75 Path/File access error
76 Path not found
91 Object variable not set
92 For loop not initialized
94 Invalid use of Null
322 Can't create necessary temporary file
424 Object required
429 ActiveX component can't create object
430 Class doesn't support Automation
432 File name or class name not found during Automation operation
438 Object doesn't support this property or method
440 Automation error
445 Object doesn't support this action
446 Object doesn't support named arguments
447 Object doesn't support current locale setting
448 Named argument not found
449 Argument not optional
450 Wrong number of arguments or invalid property assignment
451 Object not a collection
453 Specified DLL function not found
455 Code resource lock error
457 This key is already associated with an element of this collection
458 Variable uses an Automation type not supported in VBScript
462 The remote server machine does not exist or is unavailable
481 Invalid picture
500 Variable is undefined
501 Illegal assignment
502 Object not safe for scripting
503 Object not safe for initializing
504 Object not safe for creating
505 Invalid or unqualified reference
506 Class not defined
507 An exception occurred
32811 Element not found
32812 The specified date is not available in the current locale's calendar

There are errors missing from the table -- errors which VB6 raises that VBScript never raises, like "Return without gosub" or "Bad DLL calling convention". And there are errors added that make no sense in VB6, like "not safe for scripting". But more or less, it's the same as the VB6 run-time error table where possible. Obviously that's for backwards compatibility reasons.

Altair BASIC was Microsoft's first product, written by Bill Gates and Paul Allen back in 1975 for the Altair 8080. (Trivia: Microsoft's corporate switchboard number 425-882-8080 is an homage to the Altair!) Here's the Microsoft Altair BASIC error table, both parser and runtime errors:

1 NEXT without FOR
2 Syntax error
3 RETURN without GOSUB
4 Out of data
5 Illegal function call
6 Overflow
7 Out of memory
8 Undefined line
9 Subscript out of range
10 Redimensioned array
11 Division by zero
12 Illegal direct
13 Type mismatch
14 Out of string space
15 String too long
16 String formula too complex
17 Can't continue
18 Undefined user function
19 No RESUME
20 RESUME without error
21 Unprintable error
22 Missing operand
23 Line buffer overflow
26 FOR without NEXT
29 WHILE without WEND
30 WEND without WHILE
50 Field overflow
51 Internal error
52 Bad file number
53 File not found
54 Bad file mode
55 File already open
57 Disk I/O error
58 File already exists
61 Disk full
62 Input past end
63 Bad record number
64 Bad file name
66 Direct statement in file
67 Too many files

I had no idea that the chain of backwards compatibility went back to the original Bill & Paul code! 30 years of backwards compatibility -- not bad!