# Sometimes you just can't get an exact match on an SWI-Prolog error message **URL:** \ **Category:** Nice to know\ **Created:** [March 1, 2023, 11:36am UTC](https://swi-prolog.discourse.group/t/sometimes-you-just-cant-get-an-exact-match-on-an-swi-prolog-error-message/6322 "2023-03-01T11:36:04Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![EricGT](https://avatars.discourse-cdn.com/v4/letter/e/f1d935/32.png) [@EricGT](https://swi-prolog.discourse.group/u/EricGT)\ **Post date:** [March 1, 2023, 11:36am UTC](https://swi-prolog.discourse.group/t/sometimes-you-just-cant-get-an-exact-match-on-an-swi-prolog-error-message/6322/1 "2023-03-01T11:36:04Z")
Short answer: Check [messages.pl](https://github.com/SWI-Prolog/swipl-devel/blob/91384c7e009389953ae7d1a5eceb641b4184f882/boot/messages.pl) * * * In tyring to locate the source of this error message `% The following threads wouldn't die: ['httpd@8080_1']` First searched GitHub for `The following threads wouldn't die` with no luck. Then Googled for `The following threads wouldn't die` which a few entries down listed [swipl/messages.pl at cb3c3352e8158fc2f79ed64ba24091895dc9baad · SWI-Prolog/swipl · GitHub](https://github.com/SWI-Prolog/swipl/blob/cb3c3352e8158fc2f79ed64ba24091895dc9baad/boot/messages.pl) [messages.pl](https://github.com/SWI-Prolog/swipl/blob/cb3c3352e8158fc2f79ed64ba24091895dc9baad/boot/messages.pl) had the error message as ```prolog prolog_message(threads_not_died(Running)) --> ['The following threads wouldn\'t die: ~p'-[Running] ]. ``` which explains why finding the message was a bit hard. ---
**Author:** ![jan](https://yyz2.discourse-cdn.com/free1/user_avatar/swi-prolog.discourse.group/jan/32/4_2.png) [@jan](https://swi-prolog.discourse.group/u/jan)\ **Post date:** [March 1, 2023, 12:04pm UTC](https://swi-prolog.discourse.group/t/sometimes-you-just-cant-get-an-exact-match-on-an-swi-prolog-error-message/6322/2 "2023-03-01T12:04:50Z")
`git grep` also does miracles 🙂 The actual cause is hinted at with halt/1: threads are aborted and joined, but those not responding within a second are forcefully cancelled. Typically is because they are running foreign code that does not do signal processing. ---
**Author:** ![EricGT](https://avatars.discourse-cdn.com/v4/letter/e/f1d935/32.png) [@EricGT](https://swi-prolog.discourse.group/u/EricGT)\ **Post date:** [March 2, 2023, 11:16am UTC](https://swi-prolog.discourse.group/t/sometimes-you-just-cant-get-an-exact-match-on-an-swi-prolog-error-message/6322/4 "2023-03-02T11:16:12Z")
2 posts were merged into an existing topic: [The following threads wouldn’t die: [‘httpd@8080\_1’]](https://swi-prolog.discourse.group/t/the-following-threads-wouldnt-die-httpd-8080-1/6327/2)