Questions tagged [error-handling]
Programming language constructs designed to handle errors signaled by error codes, exceptions or other language specific means.
error-handling
27,346
questions
2695
votes
52
answers
614k
views
Does a finally block always get executed in Java?
Considering this code, can I be absolutely sure that the finally block always executes, no matter what something() is?
try {
something();
return success;
}
catch (Exception e) {
...
- 27.4k
2000
votes
27
answers
3.5m
views
How do I get PHP errors to display?
I have checked my PHP ini file (php.ini) and display_errors is set and also error reporting is E_ALL. I have restarted my Apache webserver.
I have even put these lines at the top of my script, and it ...
- 56.9k
1428
votes
11
answers
2.0m
views
How do I print an exception in Python?
How do I print the error/exception in the except: block?
try:
...
except:
print(exception)
- 265k
1283
votes
39
answers
279k
views
Reference - What does this error mean in PHP?
What is this?
This is a number of answers about warnings, errors, and notices you might encounter while programming PHP and have no clue how to fix them. This is also a Community Wiki, so everyone is ...
962
votes
21
answers
663k
views
How can I exclude all "permission denied" messages from "find"?
I need to hide all permission denied messages from:
find . > files_and_folders
I am experimenting when such message arises. I need to gather all folders and files, to which it does not arise.
...
- 137k
822
votes
8
answers
423k
views
Automatic exit from Bash shell script on error [duplicate]
I've been writing some shell script and I would find it useful if there was the ability to halt the execution of said shell script if any of the commands failed. See below for an example:
#!/bin/bash
...
- 18k
649
votes
41
answers
706k
views
How can I get useful error messages in PHP?
Quite often I will try and run a PHP script and just get a blank screen back. No error message; just an empty screen. The cause might have been a simple syntax error (wrong bracket, missing semicolon),...
- 8,650
637
votes
18
answers
656k
views
Is there a TRY CATCH command in Bash
I'm writing a shell script and need to check that a terminal app has been installed. I want to use a TRY/CATCH command to do this unless there is a neater way.
- 10.5k
629
votes
13
answers
546k
views
What is the difference between `throw new Error` and `throw someObject`?
I want to write a common error handler which will catch custom errors thrown on purpose at any instance of the code.
When I did throw new Error('sample') like in the following code
try {
throw ...
- 10.8k
625
votes
7
answers
506k
views
Begin, Rescue and Ensure in Ruby?
I've recently started programming in Ruby, and I am looking at exception handling.
I was wondering if ensure was the Ruby equivalent of finally in C#? Should I have:
file = File.open("myFile.txt", "...
- 18.5k
614
votes
13
answers
875k
views
How to check the exit status using an 'if' statement
What would be the best way to check the exit status in an if statement in order to echo a specific output?
I'm thinking of it being:
if [ $? -eq 1 ]
then
echo "blah blah blah"
fi
The ...
- 6,405
587
votes
15
answers
219k
views
Is it not possible to stringify an Error using JSON.stringify?
Reproducing the problem
I'm running into an issue when trying to pass error messages around using web sockets. I can replicate the issue I am facing using JSON.stringify to cater to a wider audience:
...
- 19.4k
555
votes
36
answers
197k
views
Should a retrieval method return 'null' or throw an exception when it can't produce the return value? [closed]
I am using java language,I have a method that is supposed to return an object if it is found.
If it is not found, should I:
return null
throw an exception
other
Which is the best practise or idiom?
536
votes
31
answers
763k
views
How do I debug "Error: spawn ENOENT" on node.js?
When I get the following error:
events.js:72
throw er; // Unhandled 'error' event
^
Error: spawn ENOENT
at errnoException (child_process.js:1000:11)
at Process....
- 17.4k
526
votes
16
answers
210k
views
Pipe output and capture exit status in Bash
I want to execute a long running command in Bash, and both capture its exit status, and tee its output.
So I do this:
command | tee out.txt
ST=$?
The problem is that the variable ST captures the ...
- 267k
524
votes
27
answers
218k
views
What's a good way to extend Error in JavaScript?
I want to throw some things in my JS code and I want them to be instanceof Error, but I also want to have them be something else.
In Python, typically, one would subclass Exception.
What's the ...
- 22.3k
501
votes
19
answers
640k
views
What does "Fatal error: Unexpectedly found nil while unwrapping an Optional value" mean?
My Swift program is crashing with EXC_BAD_INSTRUCTION and one of the following similar errors. What does this error mean, and how do I fix it?
Fatal error: Unexpectedly found nil while unwrapping ...
475
votes
30
answers
1.3m
views
Where does PHP store the error log? (PHP 5, Apache, FastCGI, and cPanel)
I am on shared hosting and have cPanel, Apache, and PHP is run by FastCGI. Where does PHP store the error log?
Is there another way I can find the error log on a shared hosting environment instead of ...
- 7,097
421
votes
14
answers
272k
views
Can I try/catch a warning?
I need to catch some warnings being thrown from some php native functions and then handle them.
Specifically:
array dns_get_record ( string $hostname [, int $type= DNS_ANY [, array &$authns [...
- 30.5k
417
votes
19
answers
340k
views
Why is "except: pass" a bad programming practice?
I often see comments on other Stack Overflow questions about how the use of except: pass is discouraged. Why is this bad? Sometimes I just don't care what the errors are and I want to just continue ...
- 6,526
397
votes
9
answers
348k
views
Is 418 "I'm a teapot" really an HTTP response code?
Is 418 "I'm a teapot" really an HTTP response code?
There are various references to this on the internet, including in lists of response codes, but I can't figure out whether it's a weird joke.
- 7,971
389
votes
4
answers
326k
views
Raise warning in Python without interrupting program
I am trying to raise a Warning in Python without making the program crash / stop / interrupt.
I use the following simple function to check if the user passed a non-zero number to it. If so, the ...
- 7,957
386
votes
10
answers
1.4m
views
400 BAD request HTTP error code meaning?
I have a JSON request which I'm posting to a HTTP URL.
Should this be treated as 400 where requestedResource field exists but "Roman" is an invalid value for this field?
[{requestedResource:"Roman"...
- 8,793
384
votes
12
answers
353k
views
Are there any standard exit status codes in Linux?
A process is considered to have completed correctly in Linux if its exit status was 0.
I've seen that segmentation faults often result in an exit status of 11, though I don't know if this is simply ...
- 125k
327
votes
15
answers
538k
views
What's the cause of the error 'getaddrinfo EAI_AGAIN'?
My server threw this today, which is a Node.js error I've never seen before:
Error: getaddrinfo EAI_AGAIN my-store.myshopify.com:443
at Object.exports._errnoException (util.js:870:11)
at ...
- 57.2k
325
votes
7
answers
113k
views
How to provide a localized description with an Error type in Swift?
I am defining a custom error type with Swift 3 syntax and I want to provide a user-friendly description of the error which is returned by the localizedDescription property of the Error object. How can ...
- 36.8k
301
votes
20
answers
488k
views
How do I solve "error: externally-managed-environment" every time I use pip 3?
Error message:
error: externally-managed-environment
× This environment is externally managed
╰─> To install Python packages system-wide, try apt install
python3-xyz, where xyz is the package ...
- 3,137
295
votes
15
answers
451k
views
Error handling in Bash [closed]
What is your favorite method to handle errors in Bash?
The best example of handling errors I have found on the web was written by William Shotts, Jr at http://www.linuxcommand.org.
He suggests ...
295
votes
26
answers
267k
views
live output from subprocess command
I'm using a python script as a driver for a hydrodynamics code. When it comes time to run the simulation, I use subprocess.Popen to run the code, collect the output from stdout and stderr into a ...
- 18.2k
281
votes
9
answers
446k
views
How do I log errors and warnings into a file?
How do I turn on all error and warnings and log them to a file, but to set up all of that within the script (not changing anything in php.ini)?
I want to define a file name and so that all errors and ...
- 2,835
276
votes
13
answers
767k
views
How to get the jQuery $.ajax error response text?
I am sending an error response to my jQuery.
However, I can not get the response text (in the example below this would be Gone to the beach)
The only thing jQuery says is 'error'.
See this example ...
- 37.4k
248
votes
3
answers
100k
views
Catch all JavaScript errors and send them to server [closed]
I wondered if anyone had experience in handling JavaScript errors globally and send them from the client browser to a server.
I think my point is quite clear, I want to know every exception, error, ...
- 4,638
242
votes
8
answers
517k
views
How do I catch an Ajax query post error?
I would like to catch the error and show the appropriate message if the Ajax request fails.
My code is like the following, but I could not manage to catch the failing Ajax request.
function ...
- 9,005
239
votes
13
answers
246k
views
Log exception with traceback in Python
How can I log my Python exceptions?
try:
do_something()
except:
# How can I log my exception here, complete with its traceback?
- 265k
230
votes
22
answers
654k
views
Deploying website: 500 - Internal server error
I am trying to deploy an ASP.NET application. I have deployed the site to IIS, but when visiting it with the browser, it shows me this:
Server Error
500 - Internal server error.
There is a problem ...
- 6,450
227
votes
11
answers
184k
views
JAX-RS / Jersey how to customize error handling?
I'm learning JAX-RS (aka, JSR-311) using Jersey. I've successfuly created a Root Resource and am playing around with parameters:
@Path("/hello")
public class HelloWorldResource {
@GET
@...
- 30.9k
223
votes
13
answers
99k
views
Cryptic "Script Error." reported in Javascript in Chrome and Firefox
I have a script that detects Javascript errors on my website and sends them to my backend for reporting. It reports the first error encountered, the supposed line number, and the time.
EDIT to ...
- 13.4k
220
votes
11
answers
600k
views
Error: could not find function ... in R
This is meant to be a FAQ question, so please be as complete as possible. The answer is a community answer, so feel free to edit if you think something is missing.
This question was discussed and ...
214
votes
3
answers
107k
views
How to create an exit message
Is there a one line function call that quits the program and displays a message? I know in Perl it's as simple as:
die("Message goes here")
I'm tired of typing this:
puts "Message goes here"
exit
- 88.7k
212
votes
21
answers
32k
views
Is assert evil? [closed]
The Go language creators write:
Go doesn't provide assertions. They are undeniably convenient, but our experience has been that programmers use them as a crutch to avoid thinking about proper error ...
207
votes
15
answers
367k
views
Detailed 500 error message, ASP + IIS 7.5
IIS 7.5 , 2008rc2, classic asp, 500 error msg:
The page cannot be displayed because an internal server error has occurred.
I need to know how to configure IIS to get a more detailed error.
I've ...
- 2,757
204
votes
1
answer
62k
views
try, try! & try? what’s the difference, and when to use each?
In Swift 2.0, Apple introduced a new way to handle errors (do-try-catch).
And few days ago in Beta 6 an even newer keyword was introduced (try?).
Also, knew that I can use try!.
What's the difference ...
- 6,466
202
votes
7
answers
157k
views
How can I make use of Error boundaries in functional React components?
I can make a class an error boundary in React by implementing componentDidCatch.
Is there a clean approach to making a functional component into an error boundary without converting it into a class?
...
- 27k
195
votes
6
answers
172k
views
How to capture no file for fs.readFileSync()?
Within node.js readFile() shows how to capture an error, however there is no comment for the readFileSync() function regarding error handling. As such, if I try to use readFileSync() when there is no ...
- 4,138
195
votes
13
answers
95k
views
Error-Handling in Swift-Language
I haven't read too much into Swift but one thing I noticed is that there are no exceptions.
So how do they do error handling in Swift? Has anyone found anything related to error-handling?
- 11.3k
186
votes
23
answers
148k
views
Error handling in C code
What do you consider "best practice" when it comes to error handling errors in a consistent way in a C library.
There are two ways I've been thinking of:
Always return error code. A typical function ...
- 11.1k
184
votes
6
answers
216k
views
Raise error in a Bash script
I want to raise an error in a Bash script with message "Test cases Failed !!!". How to do this in Bash?
For example:
if [ condition ]; then
raise error "Test cases failed !!!"
fi
- 2,730
183
votes
6
answers
207k
views
When should I use Write-Error vs. Throw? Terminating vs. non-terminating errors
Looking at a Get-WebFile script over on PoshCode, http://poshcode.org/3226, I noticed this strange-to-me contraption:
$URL_Format_Error = [string]"..."
Write-Error $URL_Format_Error
return
What is ...
- 3,463
182
votes
5
answers
88k
views
How do I log ALL exceptions globally for a C# MVC4 WebAPI app?
Background
I am developing an API Service Layer for a client and I have been requested to catch and log all errors globally.
So, while something like an unknown endpoint (or action) is easily ...
- 23.8k
179
votes
31
answers
436k
views
Eclipse returns error message "Java was started but returned exit code = 1"
This is a picture of the error code
Here is the content of the error message:
Java was started but returned exit code=1
C:\WINDOWS\system32\javaw.exe
-Dosgi.requiredJavaVersion=1.6
-Xms40m
-Xmx768m
-...
- 1,891