# Package install errors - How to resolve after SWI-Prolog changed to using HTTPS **URL:** \ **Category:** Nice to know\ **Created:** [July 1, 2019, 10:59am UTC](https://swi-prolog.discourse.group/t/package-install-errors-how-to-resolve-after-swi-prolog-changed-to-using-https/895 "2019-07-01T10:59:44Z")\ **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:** [July 1, 2019, 10:59am UTC](https://swi-prolog.discourse.group/t/package-install-errors-how-to-resolve-after-swi-prolog-changed-to-using-https/895/1 "2019-07-01T10:59:44Z")
Posting this info here so that it can be indexed by search engines and more easily found. Recently SWI-Prolog switched to using [HTTPS](https://swi-prolog.discourse.group/t/www-swi-prolog-org-goes-https/811) which broke some things for older versions of SWI-Prolog (pre 8.0.3), namely the ability to install packages. Here are examples of the errors: ```prolog Welcome to SWI-Prolog (threaded, 64 bits, version 8.0.0) SWI-Prolog comes with ABSOLUTELY NO WARRANTY. This is free software. Please run ?- license. for legal details. For online help and background, visit http://www.swi-prolog.org For built-in help, use ?- help(Topic). or ?- apropos(Word). ?- pack_install(list_util). % Contacting server at http://www.swi-prolog.org/pack/query ... ERROR: url `'https://www.swi-prolog.org/pack/query'' does not exist (status(500,Internal Server Error)) ERROR: In: ERROR: [18] throw(error(existence_error(url,'https://www.swi-prolog.org/pack/query'),context(_8290,...))) ERROR: [16] http_open:try_http_proxy(direct,[uri('http://www.swi-prolog.org/pack/query'),...|...],_8326,[post(...),...]) at c:/program files/swipl/library/http/http_open.pl:425 ERROR: [14] ERROR: [13] '$sig_atomic'(prolog_pack:http_open('http://www.swi-prolog.org/pack/query',_8420,...)) ERROR: [12] setup_call_catcher_cleanup(prolog_pack:http_open('http://www.swi-prolog.org/pack/query',_8464,...),prolog_pack:read_reply(_8476,_8478,_8480),_8450,prolog_pack:close(_8490)) at c:/program files/swipl/boot/init.pl:467 ERROR: [10] prolog_pack:query_pack_server(locate(list_util),_8522,[]) at c:/program files/swipl/library/prolog_pack.pl:1719 ERROR: [9] prolog_pack:pack_default_options(list_util,list_util,[],_8564) at c:/program files/swipl/library/prolog_pack.pl:516 ERROR: [8] prolog_pack:pack_install(list_util) at c:/program files/swipl/library/prolog_pack.pl:457 ERROR: [7] ERROR: ERROR: Note: some frames are missing due to last-call optimization. ERROR: Re-run your program in debug mode (:- debug.) to get more detail. ?- ?- pack_list(X). % Contacting server at http://www.swi-prolog.org/pack/query ... ERROR: url `'https://www.swi-prolog.org/pack/query'' does not exist (status(500,Internal Server Error)) ERROR: In: ERROR: [18] throw(error(existence_error(url,'https://www.swi-prolog.org/pack/query'),context(_1278,...))) ERROR: [16] http_open:try_http_proxy(direct,'','','') at c:/program files/swipl/library/http/http_open.pl:425 ERROR: [14] ERROR: [13] '$sig_atomic'(prolog_pack:http_open('http://www.swi-prolog.org/pack/query',_1376,...)) ERROR: [12] setup_call_catcher_cleanup('',prolog_pack:read_reply(_1418,_1420,_1422),_1406,prolog_pack:close(_1432)) at c:/program files/swipl/boot/init.pl:467 ERROR: [10] prolog_pack:query_pack_server('',_1464,[]) at c:/program files/swipl/library/prolog_pack.pl:1719 ERROR: [9] prolog_pack:pack_search(_1496) at c:/program files/swipl/library/prolog_pack.pl:365 ERROR: [7] ERROR: ERROR: Note: some frames are missing due to last-call optimization. ERROR: Re-run your program in debug mode (:- debug.) to get more detail. ?- ``` To resolve these errors SWI-Prolog needs to be upgraded. While most users work on Unix, I use Windows and will demonstrate this using Windows. Uninstall SWI-Prolog 1. Close all running instances of SWI-Prolog. 2. Locate `Uninstall.exe` for SWI-Prolog. On my system it is located in `C:\Program Files\swipl` 3. Run `Uninstall.exe` and respond to prompts. 4. Verify that the SWI-Prolog directory is empty. Delete any remaining files manually. Install latest version of SWI-Prolog 1. Navigate to [https://www.swi-prolog.org/Download.html](https://www.swi-prolog.org/Download.html) 2. Click [Stable release](https://www.swi-prolog.org/download/stable) 3. Click [SWI-Prolog **8.0.3-1** for Microsoft Windows (64 bit)](https://www.swi-prolog.org/download/stable/bin/swipl-8.0.3-1.x64.exe). This will start a download. 4. When download completes run `swipl-8.0.3-1.x64.exe`. On my system it is located in `C:\Users\Eric\Downloads` 5. Start SWI-Prolog ```prolog Welcome to SWI-Prolog (threaded, 64 bits, version 8.0.3) SWI-Prolog comes with ABSOLUTELY NO WARRANTY. This is free software. Please run ?- license. for legal details. For online help and background, visit http://www.swi-prolog.org For built-in help, use ?- help(Topic). or ?- apropos(Word). ``` Query and install of packages should work. ```prolog ?- pack_list(list_util). % Contacting server at https://www.swi-prolog.org/pack/query ... ok p list_util@0.13.0 - Predicates for working with lists true. ?- pack_install(list_util). % Contacting server at https://www.swi-prolog.org/pack/query ... ok Select download location for list_util@0.13.0 (1) * GIT repository at https://github.com/mndrix/list_util.git (2) https://github.com/mndrix/list_util/archive/v0.13.0.zip (3) Cancel Your choice? 1 % Cloning into 'c:/users/eric/appdata/roaming/swi-prolog/pack/list_util'... % Contacting server at https://www.swi-prolog.org/pack/query ... ok % "list_util.git" was downloaded 67 times Package: list_util Title: Predicates for working with lists Installed version: 0.13.0 Author: Michael Hendricks Maintainer: Michael Hendricks Packager: Michael Hendricks Home page: https://github.com/mndrix/list_util Download URL: https://github.com/mndrix/list_util/archive/v0.13.0.zip Activate pack "list_util" Y/n? true. ``` * * * **Added many many months later** [Install SWI-Prolog development version on Windows 10](https://swi-prolog.discourse.group/t/install-swi-prolog-development-version-on-windows-10/1131) [Install SWI-Prolog development version on Ubuntu using PPA](https://swi-prolog.discourse.group/t/install-swi-prolog-development-version-on-ubuntu-using-ppa/2402) ---
**Author:** ![jamesnvc](https://yyz2.discourse-cdn.com/free1/user_avatar/swi-prolog.discourse.group/jamesnvc/32/14_2.png) [@jamesnvc](https://swi-prolog.discourse.group/u/jamesnvc)\ **Post date:** [July 1, 2019, 3:02pm UTC](https://swi-prolog.discourse.group/t/package-install-errors-how-to-resolve-after-swi-prolog-changed-to-using-https/895/2 "2019-07-01T15:02:54Z")
Do you want to pin this for a few weeks? ---
**Author:** ![EricGT](https://avatars.discourse-cdn.com/v4/letter/e/f1d935/32.png) [@EricGT](https://swi-prolog.discourse.group/u/EricGT)\ **Post date:** [July 1, 2019, 3:05pm UTC](https://swi-prolog.discourse.group/t/package-install-errors-how-to-resolve-after-swi-prolog-changed-to-using-https/895/4 "2019-07-01T15:05:41Z")
Pinned globally on July 1, 2019, 3:05pm UTC