Japt, 22 bytes

Dusting off the golfing cobwebs after a week's holidays; there's probably a shorter solution.

888888888888888888888z 

Error:

No such function: N.z 

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Shakespeare Programming Language, 73 bytes

Errors. Ajax, the web technology. Act XLII:;. Scene LXIX:;. Ajax:You cat. 

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Error message, 72 bytes

Runtime error at line 7: Ajax is not on stage, and thus cannot speak! 

with one leading and two trailing newlines. Not sure whether the newlines count.

ed, 3 bytes

? 

Returns the following error message (2 bytes).

? 

ed is Turing complete, so there shouldn't be issues about whether using it is valid or not. There was a solution in ed before, but it was removed, as there was a concern whether this is a fatal error. I would say, yes, it is, no matter what I did on TIO.run, the execution did not continue after getting an error message. From checking why this happens, it appears that the execution continues only when the code is read from STDIN (REPL mode).

Inspired by https://www.gnu.org/fun/jokes/ed-msg.html

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Note that the output contains 0, but it's not a part of an error message, rather it's ed displaying file size by default. It can be removed by using -s flag. If you try changing the input provided to the program, it will change.

@, 29 bytes

Error: Unknown instruction E! 

This tries to call the function E, which does not exist.

Output message:

Error: Unknown instruction E 

Red, 29 Bytes

a/1/1/1/1/1/1/1/1/1/1/1/1/1/1 

Script Error: a has no value 

Shakespeare Programming Language, 100 bytes

,.Ajax,.Puck,.Act I:.Scene I:.[Enter Ajax and Puck]Ajax:You cat!You is the quotient betweenyou zero. 

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which produces

Runtime error at line 1: Unable to divide 1 by zero! 

The error is 53 bytes including the trailing newline.

I really don't see how this can be improved (unless I missed something obvious). It loads 1 into Puck and attempts to divide him by 0.

Rust, 61 57 bytes

fn main()->Result<(),usize>{[].binary_search(&0)?;Ok(())} 

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Returns from the main function with Error: 0.

-3 bytes thanks to Anders Kaesorg

Python 3, 71 bytes

a=b=c=d=e=f=g=h=i=j=k=l=m=n=o=p=q=r=s=t=u=v=w=x=y=z=A=B=C=D=E=F=1# is=0 

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 File ".code.tio", line 2 is=0 ^ SyntaxError: invalid syntax 

Bash, 20 bytes

"" # waste of space! 

Outputs : command not found.

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Bash, 21 bytes

b # let's waste space 

Outputs: b: command not found.

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Lua, 45 bytes

0/########################################### 

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Error message, 44 bytes

lua: .code.tio:1: unexpected symbol near '0' 

Haystack, 21 bytes

Wasted space is good! 

Errors with Where's the needle?. Dosen't work on TIO.

C/*nix, 13 bytes

f(){free(f);} 

On minimalist/old systems and shells that don't do fancy things, this prints:

Aborted 

Of course, most modern shells print things like:

*** Error in `/tmp/file': munmap_chunk(): invalid pointer: 0x0000000000400536 *** Aborted 

TryItOnline prints a whole host of information.

2Col, 50 bytes

Invalid code! Line 0 contains invalid 2Col code! 1 

Try it on 2ColIDE

Outputs:

Invalid code! Line 0 contains invalid 2Col code! 

With a trailing newline.

Explanation

2Col only really has 1 error, and it's caused by the structure of the code being wrong. 2Col expects every line to be exactly 2 characters long, so if a line is longer or shorter than that, you get the above error.

Given that for this challenge the code must be longer than the error, the easiest way to achieve that is to use the error itself and add a byte.

Python 3, 67 bytes

` File ".code.tio", line 1 ^````` SyntaxError: invalid syntax 

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Error Message, 66 bytes

 File ".code.tio", line 1 ` ^ SyntaxError: invalid syntax 

Mathematica, 120 bytes

"Take it easy my brother JungHwan Min,Take it easy my brother LegionMammal978,Take it easy my brother Charlie"*666*666/0 

error-> Power::infy: Infinite expression 1/0 encountered.

see comments for details...

Casio Basic, 10 bytes

{}=>a:a[1] 

or, for 12 bytes:

seq(x,x,1,0) 

Error for both (6 bytes):

Domain 

For the first one, accessing a list element outside the length of the list throws a Domain error. But for some weird reason, you can't access a list index in one go; that is, {}[1] is invalid syntax.

seq generates a list of values for a function with values in a given range; but in this case, specifying a range of 1 to 0 causes a Domain error, since the end is smaller than the start.

Braingolf, 54 bytes

"ZeroDivisionError: integer division or modulo by z"0/ 

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Throws the 53 byte error ZeroDivisionError: integer division or modulo by zero

Explanation

"ZeroDivisionError: integer division or modulo by z" is a string literal, pushes the error minus 3 bytes.

0 pushes 0, and / attempts to divide the 2nd to last item by the last item, in this case dividing z (122) by 0, which results in a divide by zero error.

Braingolf, 84 bytes

"ValueError: Indices for islice() must be None or an integer: 0 <= x <= sys.maxs"&@@ 

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I personally get this error quite often when screwing around with ASCII art challenges in Braingolf.

Throws a ValueError: Indices for islice() must be None or an integer: 0 <= x <= sys.maxsize. error.

Explanation

"ValueError: Indices for islice() must be None or an integer: 0 <= x <= sys.max" is a string literal. It's just the error minus 4 bytes, because the code must be longer than the error.

&@ then pops and prints the entire stack.

Finally @ attempts to pop and print an item from the now empty stack. Popping from an empty stack produces the above 83 byte error.

C++, 26 bytes

int main(){div(1,0);} //?? 

Result in Windows:

a.exe has stopped working 

VBA, 29 Bytes

Anonymous VBE immediate window function of length 29 which throws Runtime error 6, (len 28) to STDERR

Code

?CByte(Len(Space(127+128+1))) 

Error

Run-time error '6':

Overflow

Prolog (SWI), 26 bytes (error: 25 bytes)

a :- a ; a ; a ; a ; a ;a. 

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This will generate the error: ERROR: Out of local stack (which is, as far as I know, the shortest error message that can be generated by SWI-Prolog).

Explanation

The above program can be simplified to a :- a ; a. (the other ; as are here so that the program is longer than the error message).

The above program says:

a :- . % For a to be true… a % Either a… ; % …or… a % …a must be true 

This is obviously infinitely recursive, hence why we get an Out of local stack error.

However, the following program:

a :- a. 

is also infinitely recursive but will never crash. This is because in that case, tail recursion optimization occurs so that the recursive call does not consume memory.

a :- a ; a. is also tail recursive; however we have introduced a disjunction with ; which prevents the recursive call from not consuming memory, because Prolog has to remember that there was another choice possible to explore instead of each recursive call.

It is possible to generate this same error with other approaches (e.g. using length(_,1000000000) to generate a list too big to fit in memory), but this one is probably the coolest looking one.

Groovy, 69 bytes

java.lang.Class.metaClass=Integer.metaClass Integer.metaClass.plus={1} 

Error message is:

java.lang.StackOverflowError 

I don't know if this will count at 31 bytes, because it will output a lot of line numbers:

a​aaaaaa={aaaaaaa()}​;aaaaaaa() 

Output:

java.lang.StackOverflowError at Script1$_run_closure1.doCall(Script1.groovy:1) at Script1$_run_closure1.doCall(Script1.groovy) at Script1$_run_closure1.doCall(Script1.groovy:1) at Script1$_run_closure1.doCall(Script1.groovy) ... 

​

MATLAB, 52 44 43 bytes

Another shorter option is to use a function and not provide enough inputs. For example:

qr()%I'm a nice comment to make code longer 

Gives this 42 byte error:

Error using qr Not enough input arguments. 

This code (or to be fair any similar code:

[1 1]*[2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 ] 

Produces the following 51 byte error:

Error using * Inner matrix dimensions must agree. 

It's actually surprisingly tricky in MATLAB because when you run any code with syntax errors the error output includes the line of code you ran - which would put a theoretical lower limit on code size of infinity. Fortunately matrix multiplication errors don't do that.

Vim, 19 bytes?

:print "ex command 

With a trailing newline, this prints the current line to the messages window. If the buffer is empty, it shows E749: empty buffer instead. The " starts a comment.

I'm an very unsure how to count the number of bytes both in the input and error message. The command can be run as vim +"print \"ex command" (17 bytes?), but this adds an additional line to the error message: Error detected while processing command line: (total 62 bytes?).

Alternatively, the command can be put in a file and run the the following hack to trick Vim it is user input: cat cmd.vim - | vim --not-a-term. Without --not-a-term Vim writes Vim: Warning: Input is not from a terminal.

I didn't count the error message length including a newline since Vim won't write a newline to the screen; it uses ncurses or similar to directly draw at specific coordinates.

There is one potentially shorter error message: E572: Exit code %d. It can be triggered by :tcl, but I'll leave it to someone who has +tcl enabled.

C# (.Net, Mono) 25 bytes

class Hi{void There(){_}} 

Error:

error CS1002: ; expected 

Note: Mono error messages include filename and location before them, so if you named the file P.cs, you'd get this error:

P.cs(1,24): error CS1002: ; expected 

Since that part depends on the filename and location of text, I didn't include it. However, if you include it (and make the class name longer or something), you end up with a 36 byte error message and 37 byte program. Let me know if I should change it to that.

Aceto, 41 bytes

 & 

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Produces __main__.CodeException: Raised an &rror.

The error message is 40 chars, so...

SmileBASIC console, 12 11 bytes

?@L*EXP(22) 

Error message (8 or 9 bytes):

Overflow 

Must be run from the console, otherwise it outputs a line number. Normally errors are formatted like {error} in {slot}:{line}({func}:{arg}), but this error isn't caused by a function and doesn't have a line number so only the error name is shown.

EXP(x) returns e^x, and e^22 is 3584912846.131588. This is outside the 32 bit signed integer range of -2147483648 to 2147483647. Multiplying a string (@L) by this value converts it to an integer, causing an overflow error.

naz, 38 bytes

1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a4x 

Explanation

1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a # Add 1 to the register 18 times 4x # Set the current opcode to 4 

The only opcodes accepted by the naz interpreter under any circumstances are 0 (normal operation), 1 (function write), 2 (variable write), and 3 (conditional). Thus, if run from a file with a one-letter filename (e.g. f.naz), this program will produce the following 37-byte error:

error: invalid opcode at f.naz:1:38 

COBOL(GNU), 47 bytes

PROCEDURE DIVISION. HELLO. HELLO. HELLO. HELLO. 

Outputs:

main.cobc: 1: error: PROGRAM-ID header missing

Assuming filename = main.cobc

Setanta, 12 bytes

1/0 >--- uwu 

This produces the 11-byte error message Roinnt ar 0.

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Vyxal 3, 38 bytes

222222222222222222222222222222222222[x 

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RuntimeException: Too many recursions