# \#bug **URL:** https://swi-prolog.discourse.group/tag/bug/1.md [Latest](https://swi-prolog.discourse.group/latest.md) · [Categories](https://swi-prolog.discourse.group/categories.md) · [Tags](https://swi-prolog.discourse.group/tags.md) --- ## [How to generate full doc files of a project?](https://swi-prolog.discourse.group/t/how-to-generate-full-doc-files-of-a-project/9831)
**Author:** [@andrii](https://swi-prolog.discourse.group/u/andrii)\ **Replies:** 1\ **Last updated:** [September 21, 2026, 6:36pm UTC](https://swi-prolog.discourse.group/t/how-to-generate-full-doc-files-of-a-project/9831 "2026-09-21T18:36:35Z")
I tried using doc\_save(., \[\]), but it does not generate separate pages for predicates, while still generating the respective hrefs in index.html. Suppose I have a prolog file test.pl I want to have a documentation for, … --- ## [Break\_hook/7](https://swi-prolog.discourse.group/t/break-hook-7/9817)
**Author:** [@mike.elston](https://swi-prolog.discourse.group/u/mike.elston)\ **Replies:** 1\ **Last updated:** [September 10, 2026, 5:25pm UTC](https://swi-prolog.discourse.group/t/break-hook-7/9817 "2026-09-10T17:25:54Z")
Playing around with breakpoints I added this hook definition and test code: prolog:break\_hook(Clause, PC, FR, BFR, Expression, Debug, Action) :- writeln(user\_error, break\_hook(Clause, PC, FR, BFR, Expression, Debug)… --- ## [Epilog console freeze on dragging scroll bar track](https://swi-prolog.discourse.group/t/epilog-console-freeze-on-dragging-scroll-bar-track/9811)
**Author:** [@BobKTMGC](https://swi-prolog.discourse.group/u/BobKTMGC)\ **Replies:** 2\ **Last updated:** [September 10, 2026, 2:19am UTC](https://swi-prolog.discourse.group/t/epilog-console-freeze-on-dragging-scroll-bar-track/9811 "2026-09-10T02:19:33Z")
Maybe you are not supposed to drag the scroll bar track, but this happens accidentally and freezes the console. SWI-Prolog 10.0.2 swipl-win.exe Windows 11 Pro 25H2 Build 26200.9168 Reproducible: Produce enough out… --- ## [A new bug in my old code?](https://swi-prolog.discourse.group/t/a-new-bug-in-my-old-code/9804)
**Author:** [@Marc](https://swi-prolog.discourse.group/u/Marc)\ **Replies:** 10\ **Last updated:** [September 2, 2026, 6:12pm UTC](https://swi-prolog.discourse.group/t/a-new-bug-in-my-old-code/9804 "2026-09-02T18:12:18Z")
I’m using: SWI-Prolog version 10.0.2. I want the code to: retract all dynamic predicates that are not built-in. But what I’m getting after cleanup each time I consult a file is: ERROR: Domain error: \`file\_type’ expecte… --- ## [Emacs - File - Show buffer menu error](https://swi-prolog.discourse.group/t/emacs-file-show-buffer-menu-error/9802)
**Author:** [@mike.elston](https://swi-prolog.discourse.group/u/mike.elston)\ **Replies:** 1\ **Last updated:** [August 30, 2026, 12:20pm UTC](https://swi-prolog.discourse.group/t/emacs-file-show-buffer-menu-error/9802 "2026-08-30T12:20:47Z")
Welcome to SWI-Prolog (threaded, 64 bits, version 10.1.13-75-gb8d1d7413) Emacs - File - Show buffer menu 101 ?- emacs. true. \[PCE warning: \(0xaaaae9f45420,emacs\_buffer\_menu): No implementation for: -\>icon … --- ## [Unicode NO-BREAK SPACE not normalized by normalize\_space/2](https://swi-prolog.discourse.group/t/unicode-no-break-space-not-normalized-by-normalize-space-2/9800)
**Author:** [@mike.elston](https://swi-prolog.discourse.group/u/mike.elston)\ **Replies:** 4\ **Last updated:** [August 29, 2026, 8:06pm UTC](https://swi-prolog.discourse.group/t/unicode-no-break-space-not-normalized-by-normalize-space-2/9800 "2026-08-29T20:06:36Z")
The documentation for normalize\_space/2 says: All non-empty sequences for Unicode white space characters are replaced by a single space (\\u0020) character. but atom\_codes(A, \[0x00A0\]),normalize\_space(atom(X),A). A = … --- ## [Bug logging into https://www.swi-prolog.org/](https://swi-prolog.discourse.group/t/bug-logging-into-https-www-swi-prolog-org/9795)
**Author:** [@jbsiddall](https://swi-prolog.discourse.group/u/jbsiddall)\ **Replies:** 2\ **Last updated:** [August 23, 2026, 12:23pm UTC](https://swi-prolog.discourse.group/t/bug-logging-into-https-www-swi-prolog-org/9795 "2026-08-23T12:23:52Z")
Reproduce: Goto swi-prolog site Click login link in page footer click “sign in with “ + Google icon follow Google oauth until successful redirected can to swi I expected to see the normal swi page I started on, and ho… --- ## [Bug in clause/2?](https://swi-prolog.discourse.group/t/bug-in-clause-2/9726)
**Author:** [@Iam](https://swi-prolog.discourse.group/u/Iam)\ **Replies:** 12\ **Last updated:** [July 11, 2026, 1:06pm UTC](https://swi-prolog.discourse.group/t/bug-in-clause-2/9726 "2026-07-11T13:06:23Z")
I am using SWI-Prolog (threaded, 64 bits, version 10.0.2) on a Mac M3. My single line program is: test(L) :- ( L = a ) . My query is ?- clause(test(L),Body). I expected to get the same answer that I got in SW… --- ## [Issues with UNC path](https://swi-prolog.discourse.group/t/issues-with-unc-path/9010)
**Author:** [@nijan104](https://swi-prolog.discourse.group/u/nijan104)\ **Replies:** 9\ **Last updated:** [July 1, 2026, 6:02pm UTC](https://swi-prolog.discourse.group/t/issues-with-unc-path/9010 "2026-07-01T18:02:33Z")
Hi Jan, I am trying to upgrade my project from swi prolog version 5.6.48 to version 9.2.9-1 but came across some issues with UNC paths. First issue appeared when I was trying to load a dll from a UNC path When I … --- ## [Resolving MQI ambiguities](https://swi-prolog.discourse.group/t/resolving-mqi-ambiguities/9685)
**Author:** [@JansthcirlU](https://swi-prolog.discourse.group/u/JansthcirlU)\ **Replies:** 0\ **Last updated:** [June 9, 2026, 9:16am UTC](https://swi-prolog.discourse.group/t/resolving-mqi-ambiguities/9685 "2026-06-09T09:16:45Z")
Hi all, I’m Jan and I got started with Prolog fairly recently to learn more about logic programming. I’m a .NET developer by profession so I was immediately intrigued by the idea of creating an MQI client for C# so that … --- ## [Swipl-win: no GUI](https://swi-prolog.discourse.group/t/swipl-win-no-gui/9634)
**Author:** [@mike.elston](https://swi-prolog.discourse.group/u/mike.elston)\ **Replies:** 3\ **Last updated:** [May 27, 2026, 11:41am UTC](https://swi-prolog.discourse.group/t/swipl-win-no-gui/9634 "2026-05-27T11:41:44Z")
Hi I’ve just done a full rebuild which completed successfully but the swipl-win produced does not display the GUI interface: mike@meepi01:~$ swipl-win Welcome to SWI-Prolog (threaded, 64 bits, version 10.1.7-41-gbf4341… --- ## [Engine timeout and cross-thread destroy issues](https://swi-prolog.discourse.group/t/engine-timeout-and-cross-thread-destroy-issues/9624)
**Author:** [@torbjorn.lager](https://swi-prolog.discourse.group/u/torbjorn.lager)\ **Replies:** 2\ **Last updated:** [May 22, 2026, 11:11am UTC](https://swi-prolog.discourse.group/t/engine-timeout-and-cross-thread-destroy-issues/9624 "2026-05-22T11:11:06Z")
Supported by Claude, I’m looking for a way to implement the stateless HTTP API using engines instead of threads, as engines are cheaper to store in the cache. It’s looking good except for one thing: the engine-backed var… --- ## [Mute ws\_discard\_input()](https://swi-prolog.discourse.group/t/mute-ws-discard-input/9628)
**Author:** [@alanbur](https://swi-prolog.discourse.group/u/alanbur)\ **Replies:** 18\ **Last updated:** [May 21, 2026, 1:41pm UTC](https://swi-prolog.discourse.group/t/mute-ws-discard-input/9628 "2026-05-21T13:41:46Z")
When using the GUI debugger there’s often a continuous stream of messages from ws\_discard\_input() that seem to serve no useful purpose and make the terminal interface completely unusable. This patch fixes that. Patch is … --- ## [SEGV in tabled deterministic predicate, but only when compiled](https://swi-prolog.discourse.group/t/segv-in-tabled-deterministic-predicate-but-only-when-compiled/9514)
**Author:** [@alanbur](https://swi-prolog.discourse.group/u/alanbur)\ **Replies:** 16\ **Last updated:** [May 20, 2026, 3:33pm UTC](https://swi-prolog.discourse.group/t/segv-in-tabled-deterministic-predicate-but-only-when-compiled/9514 "2026-05-20T15:33:53Z")
Version 10.1.2 This only fails when compiled: ERROR: \\\[Thread main\\\] Deterministic procedure stats:resourceStats/1 failed ERROR: \\\[Thread main\\\] In: ERROR: \\\[Thread main\\\] \\\[20\\\] throw(error(determinism\_error(…,det,f… --- ## [BUG: internal error in GUI debugger](https://swi-prolog.discourse.group/t/bug-internal-error-in-gui-debugger/9622)
**Author:** [@alanbur](https://swi-prolog.discourse.group/u/alanbur)\ **Replies:** 4\ **Last updated:** [May 20, 2026, 3:21pm UTC](https://swi-prolog.discourse.group/t/bug-internal-error-in-gui-debugger/9622 "2026-05-20T15:21:45Z")
I’m seeing this in both 10.1.5 & 10.1.7 when stepping through code with the GUI debugger. The initial gspy breakpoint is taken OK, but this happens after the first ‘step into’: \[INTERNAL ERROR: Diff: '.'(\_, roots, A), '… --- ## [Tools - View threads missing resource](https://swi-prolog.discourse.group/t/tools-view-threads-missing-resource/9600)
**Author:** [@mike.elston](https://swi-prolog.discourse.group/u/mike.elston)\ **Replies:** 1\ **Last updated:** [May 8, 2026, 7:49am UTC](https://swi-prolog.discourse.group/t/tools-view-threads-missing-resource/9600 "2026-05-08T07:49:20Z")
In swipl-win selecting Tools - View threads results in an error. Ubuntu 25.10 Welcome to SWI-Prolog (threaded, 64 bits, version 10.1.6-76-g7628a7adf) 1 ?- \[PCE: error: running: Cannot open for read: No such file or di… --- ## [Error: exported procedure socket: XYZ not defined - when using Parallels on Apple M3, but not on Apple Intel Core i7](https://swi-prolog.discourse.group/t/error-exported-procedure-socket-xyz-not-defined-when-using-parallels-on-apple-m3-but-not-on-apple-intel-core-i7/9570)
**Author:** [@Iam](https://swi-prolog.discourse.group/u/Iam)\ **Replies:** 1\ **Last updated:** [April 13, 2026, 7:57am UTC](https://swi-prolog.discourse.group/t/error-exported-procedure-socket-xyz-not-defined-when-using-parallels-on-apple-m3-but-not-on-apple-intel-core-i7/9570 "2026-04-13T07:57:42Z")
Any help is very much appreciated! I am using SWI-Prolog 10.0.2-1 in a classroom on different platforms: Linux (no problem) MacOS on M3 (no problem) MacOS on Intel Core i7 (no problem) Parallels on Mac with Intel Core… --- ## [Crash when labelling](https://swi-prolog.discourse.group/t/crash-when-labelling/9557)
**Author:** [@AZH](https://swi-prolog.discourse.group/u/AZH)\ **Replies:** 3\ **Last updated:** [April 3, 2026, 1:52pm UTC](https://swi-prolog.discourse.group/t/crash-when-labelling/9557 "2026-04-03T13:52:22Z")
Hi there, just found probably a bug in labeling/2. The following can recreate it: test :- A = \[\_\], A ins 0..1, when(ground(A), A mod 1 #= \_), labeling(\[enum\], A). The expected outcome should be an E… --- ## [I can't install swi-prolog-x from the official ppa](https://swi-prolog.discourse.group/t/i-cant-install-swi-prolog-x-from-the-official-ppa/9532)
**Author:** [@kotenok2000](https://swi-prolog.discourse.group/u/kotenok2000)\ **Replies:** 1\ **Last updated:** [February 25, 2026, 8:52am UTC](https://swi-prolog.discourse.group/t/i-cant-install-swi-prolog-x-from-the-official-ppa/9532 "2026-02-25T08:52:06Z")
I have installed swi-prolog-nox 10.0.1-1-g18f431324-nobleppa2, but swi-prolog-x is still 9.2.9-3-g36d9cca02-nobleppa2 i get this: The following packages have unmet dependencies: swi-prolog-x : Depends: swi-prolog-nox … --- ## [Dynamic subsumptive table/1 predicate](https://swi-prolog.discourse.group/t/dynamic-subsumptive-table-1-predicate/9482)
**Author:** [@alanbur](https://swi-prolog.discourse.group/u/alanbur)\ **Replies:** 11\ **Last updated:** [January 23, 2026, 4:48pm UTC](https://swi-prolog.discourse.group/t/dynamic-subsumptive-table-1-predicate/9482 "2026-01-23T16:48:52Z")
The docs say: Although table/1 is normally used as a directive, SWI-Prolog allows calling it as a runtime predicate to prepare an existing predicate for tabled execution. What they don’t say is how to do so and make … --- ## [Nits in the profiler](https://swi-prolog.discourse.group/t/nits-in-the-profiler/9483)
**Author:** [@alanbur](https://swi-prolog.discourse.group/u/alanbur)\ **Replies:** 3\ **Last updated:** [January 19, 2026, 3:51pm UTC](https://swi-prolog.discourse.group/t/nits-in-the-profiler/9483 "2026-01-19T15:51:13Z")
Version: SWI-Prolog version 10.1.1 for x86\_64-linux The docs say “The predicates have a menu that allows changing the view of the detail window to the given caller or callee, showing the documentation (if it is a built… --- ## [Bug of variable instantiation?](https://swi-prolog.discourse.group/t/bug-of-variable-instantiation/9463)
**Author:** [@AZH](https://swi-prolog.discourse.group/u/AZH)\ **Replies:** 12\ **Last updated:** [December 28, 2025, 5:37am UTC](https://swi-prolog.discourse.group/t/bug-of-variable-instantiation/9463 "2025-12-28T05:37:14Z")
Hi, there might be a bug that looks to be related to variable instantiation. To see it, run: ?- freeze(Ns, sum(Ns, #=, 2)), append(\[1\], \[1\], Ns). You get: ERROR: Arguments are not sufficiently instantiated A workaroun… --- ## [Deadlock in futex\_wait() when using archive\_foldl() & threads](https://swi-prolog.discourse.group/t/deadlock-in-futex-wait-when-using-archive-foldl-threads/9433)
**Author:** [@alanbur](https://swi-prolog.discourse.group/u/alanbur)\ **Replies:** 5\ **Last updated:** [December 16, 2025, 10:46am UTC](https://swi-prolog.discourse.group/t/deadlock-in-futex-wait-when-using-archive-foldl-threads/9433 "2025-12-16T10:46:50Z")
I have an application that reads multiple ZIP files, iterating over each entry in each ZIP file using archive\_foldl() to read the entries. The outer loop is a call of maplist(), with an entry in the list for each ZIP fil… --- ## [Swipl-win only quarter of window (github raised issue)?](https://swi-prolog.discourse.group/t/swipl-win-only-quarter-of-window-github-raised-issue/9416)
**Author:** [@jan](https://swi-prolog.discourse.group/u/jan)\ **Replies:** 5\ **Last updated:** [December 7, 2025, 9:53am UTC](https://swi-prolog.discourse.group/t/swipl-win-only-quarter-of-window-github-raised-issue/9416 "2025-12-07T09:53:34Z")
See Install of swipl-10.0.0-1.x64 on Windows 11Pro 25H2 does not display correctly · Issue #48 · SWI-Prolog/packages-xpce · GitHub Anyone experiencing this? I suspect it is related to hires screens on Windows. I hav… --- ## [Resizing the debugger window causes it to crash](https://swi-prolog.discourse.group/t/resizing-the-debugger-window-causes-it-to-crash/9337)
**Author:** [@martin](https://swi-prolog.discourse.group/u/martin)\ **Replies:** 10\ **Last updated:** [November 28, 2025, 7:27am UTC](https://swi-prolog.discourse.group/t/resizing-the-debugger-window-causes-it-to-crash/9337 "2025-11-28T07:27:01Z")
I’m using: SWI-Prolog version 9.3.31. With Linux Cinnamon 22.1. When I tried to resize the debugger window, it crashed. I mean that the debugger window closed, and so did the prolog console. It doesnt always crash wh… --- ## [There is a bug in the debugger, only when its in a second display](https://swi-prolog.discourse.group/t/there-is-a-bug-in-the-debugger-only-when-its-in-a-second-display/9403)
**Author:** [@martin](https://swi-prolog.discourse.group/u/martin)\ **Replies:** 0\ **Last updated:** [November 27, 2025, 7:20pm UTC](https://swi-prolog.discourse.group/t/there-is-a-bug-in-the-debugger-only-when-its-in-a-second-display/9403 "2025-11-27T19:20:21Z")
This message isn’t really asking for Help, I am not sure where to put it. Its a bug report. I’m using: SWI-Prolog version 9.3.35, on Linux. I am using a laptop, and an external monitor. In the Swi prolog debugger win… --- ## [Listing regular files with directory\_member/2](https://swi-prolog.discourse.group/t/listing-regular-files-with-directory-member-2/9343)
**Author:** [@Boris](https://swi-prolog.discourse.group/u/Boris)\ **Replies:** 1\ **Last updated:** [October 5, 2025, 8:06am UTC](https://swi-prolog.discourse.group/t/listing-regular-files-with-directory-member-2/9343 "2025-10-05T08:06:56Z")
Currently, using the option file\_type(regular) causes directory\_member/2 to fail without any solutions, no matter what is in that directory. $ mkdir foo $ cd foo $ touch a b c $ swipl Welcome to SWI-Prolog (threaded, 64… --- ## [How to make it write all of a list](https://swi-prolog.discourse.group/t/how-to-make-it-write-all-of-a-list/9322)
**Author:** [@martin](https://swi-prolog.discourse.group/u/martin)\ **Replies:** 3\ **Last updated:** [September 26, 2025, 11:21am UTC](https://swi-prolog.discourse.group/t/how-to-make-it-write-all-of-a-list/9322 "2025-09-26T11:21:21Z")
I’m using: SWI-Prolog version 9.3.31. I want the code to: make the interpreter write lists without “…”. E.g. it should write “\[did, she\]” instead of “\[did|…\]”. Is there a way to do this with version 9.3.31 ? In older… --- ## [Crash when initializing GMP](https://swi-prolog.discourse.group/t/crash-when-initializing-gmp/9249)
**Author:** [@nvetrini](https://swi-prolog.discourse.group/u/nvetrini)\ **Replies:** 5\ **Last updated:** [September 22, 2025, 6:21am UTC](https://swi-prolog.discourse.group/t/crash-when-initializing-gmp/9249 "2025-09-22T06:21:15Z")
Hi, after upgrading to 2380532402c1ccf86bf8992fe6ed52a16234172f (thanks Jan for the patch) on Linux/x86\_64 I was running some regression tests on my application, and I noticed a crash tied to GMP. Naturally swipl is buil… --- ## [One button in the gui tracer has stopped working](https://swi-prolog.discourse.group/t/one-button-in-the-gui-tracer-has-stopped-working/9299)
**Author:** [@martin](https://swi-prolog.discourse.group/u/martin)\ **Replies:** 6\ **Last updated:** [September 21, 2025, 3:00pm UTC](https://swi-prolog.discourse.group/t/one-button-in-the-gui-tracer-has-stopped-working/9299 "2025-09-21T15:00:28Z")
There is one button in the gui tracer that doesn’t do anything. Its the button with the label “Enter a query (in new thread) (B)”. I am using Swipl 9.3.30, on Linux Mint 22.1. This button used to work. I am not sure, … [Next page](https://swi-prolog.discourse.group/tag/bug/1.md?match_all_tags=true&page=1&tags%5B%5D=bug)