The OCR tool available in Gadgets, does not work anymore and here are the steps to reproduce the problem:
1. Using Firefox 68.0.1, log in to English Wikisource.
2. Select OCR in Preferences\Gadgets.
[https://en.wikisource.org/w/index.php?title=Page:Mexico_under_Carranza.djvu/95&action=edit] Open this, or any other page in edit mode.
Click on the OCR and it's "frozen".
Save and close document. The OCR deletes the existing text but does not replace it. [[Page:Mexico under Carranza.djvu/85|as is seen here]].
The following are the error messages (5) in the debug console generated by activating the OCR:
JQMIGRATE: Migrate is installed with logging active, version 3.0.1 load.php:316:217
This page is using the deprecated ResourceLoader module "jquery.throttle-debounce".
Please use OO.ui.throttle/debounce instead. See https://phabricator.wikimedia.org/T213426 load.php:787:260
This page is using the deprecated ResourceLoader module "jquery.ui.position". load.php:57:298
This page is using the deprecated ResourceLoader module "jquery.ui.widget". load.php:88:949
This page is using the deprecated ResourceLoader module "jquery.ui.core".
Please use OOUI instead. load.php:11:91
JQMIGRATE: jQuery(window).on('load'...) called after load event occurred load.php:316:792
JQMIGRATE: jQuery.fn.bind() is deprecated load.php:316:792
jQuery.Deferred exception: ve.init is undefined mw.libs.ve.EditingTabDialog.prototype.getSetupProcess/<@https://en.wikisource.org/w/load.php?lang=en&modules=ext.visualEditor.switching%7Coojs-ui%7Coojs-ui.styles.icons-accessibility&skin=vector&version=0wrn2bo:4:376
proceed/<@https://en.wikisource.org/w/load.php?lang=en&modules=ext.CodeMirror%2CTemplateWizard%2Ccharinsert%2CeventLogging%2CnavigationTiming%2CwikimediaEvents%7Cext.CodeMirror.data%7Cext.centralNotice.geoIP%7Cext.centralauth.ForeignApi%7Cext.centralauth.centralautologin.clearcookie%7Cext.echo.api%2Cinit%7Cext.proofreadpage.icons%7Cext.proofreadpage.page.edit%2Cnavigation%7Cext.proofreadpage.ve.pageTarget.init%7Cext.uls.common%2Cinterface%2Cpreferences%2Cwebfonts%7Cext.visualEditor.desktopArticleTarget.init%7Cext.visualEditor.progressBarWidget%2CsupportCheck%2CtargetLoader%2CtempWikitextEditorWidget%2Ctrack%2Cve%7Cext.wikimediaEvents.loggedin%7Cjquery%2Cmoment%2Coojs%2Coojs-ui-core%2Coojs-ui-toolbars%2Coojs-ui-widgets%2Coojs-ui-windows%2Csite%7Cjquery.accessKeyLabel%2CcheckboxShiftClick%2Cclient%2Ccookie%2CgetAttrs%2ChighlightText%2ClengthLimit%2CmakeCollapsible%2Cmousewheel%2CprpZoom%2Csuggestions%2CtabIndex%2CtextSelection%2Cthrottle-debounce%7Cjquery.makeCollapsible.styles%7Cjquery.uls.data%7Cmediawiki.ForeignApi%2CForeignStructuredUpload%2CForeignUpload%2CRegExp%2CString%2CTitle%2CUpload%2CUri%2Capi%2Cbase%2Ccldr%2Ccookie%2Cexperiments%2Cicon%2CjqueryMsg%2Clanguage%2Cnotify%2CsearchSuggest%2Cstorage%2Ctemplate%2Cuser%2Cutil%2Cwidgets%7Cmediawiki.ForeignApi.core%7Cmediawiki.ForeignStructuredUpload.BookletLayout%7Cmediawiki.Upload.BookletLayout%2CDialog%7Cmediawiki.action.edit%7Cmediawiki.action.edit.collapsibleFooter%7Cmediawiki.language.specialCharacters%7Cmediawiki.legacy.wikibits%7Cmediawiki.libs.jpegmeta%2Cpluralruleparser%7Cmediawiki.page.ready%2Cstartup%7Cmediawiki.page.watch.ajax%7Cmediawiki.template.regexp%7Cmediawiki.widgets.CategoryMultiselectWidget%2CDateInputWidget%2CStashedFileWidget%2CUserInputWidget%2CvisibleLengthLimit%7Cmediawiki.widgets.DateInputWidget.styles%7Coojs-ui-toolbars.icons%7Coojs-ui-widgets.icons%7Coojs-ui-windows.icons%7Coojs-ui.styles.icons-content%2Cicons-editing-advanced%2Cicons-editing-citation%2Cicons-editing-core%2Cicons-editing-list%2Cicons-editing-styling%2Cicons-interactions%2Cicons-media%2Cicons-movement%7Cskins.vector.js%7Cuser.defaults%7Cwikibase.client.action.edit.collapsibleFooter&skin=vector&version=0as2p6p:712:96
mightThrow@https://en.wikisource.org/w/load.php?lang=en&modules=ext.CodeMirror%2CTemplateWizard%2Ccharinsert%2CeventLogging%2CnavigationTiming%2CwikimediaEvents%7Cext.CodeMirror.data%7Cext.centralNotice.geoIP%7Cext.centralauth.ForeignApi%7Cext.centralauth.centralautologin.clearcookie%7Cext.echo.api%2Cinit%7Cext.proofreadpage.icons%7Cext.proofreadpage.page.edit%2Cnavigation%7Cext.proofreadpage.ve.pageTarget.init%7Cext.uls.common%2Cinterface%2Cpreferences%2Cwebfonts%7Cext.visualEditor.desktopArticleTarget.init%7Cext.visualEditor.progressBarWidget%2CsupportCheck%2CtargetLoader%2CtempWikitextEditorWidget%2Ctrack%2Cve%7Cext.wikimediaEvents.loggedin%7Cjquery%2Cmoment%2Coojs%2Coojs-ui-core%2Coojs-ui-toolbars%2Coojs-ui-widgets%2Coojs-ui-windows%2Csite%7Cjquery.accessKeyLabel%2CcheckboxShiftClick%2Cclient%2Ccookie%2CgetAttrs%2ChighlightText%2ClengthLimit%2CmakeCollapsible%2Cmousewheel%2CprpZoom%2Csuggestions%2CtabIndex%2CtextSelection%2Cthrottle-debounce%7Cjquery.makeCollapsible.styles%7Cjquery.uls.data%7Cmediawiki.ForeignApi%2CForeignStructuredUpload%2CForeignUpload%2CRegExp%2CString%2CTitle%2CUpload%2CUri%2Capi%2Cbase%2Ccldr%2Ccookie%2Cexperiments%2Cicon%2CjqueryMsg%2Clanguage%2Cnotify%2CsearchSuggest%2Cstorage%2Ctemplate%2Cuser%2Cutil%2Cwidgets%7Cmediawiki.ForeignApi.core%7Cmediawiki.ForeignStructuredUpload.BookletLayout%7Cmediawiki.Upload.BookletLayout%2CDialog%7Cmediawiki.action.edit%7Cmediawiki.action.edit.collapsibleFooter%7Cmediawiki.language.specialCharacters%7Cmediawiki.legacy.wikibits%7Cmediawiki.libs.jpegmeta%2Cpluralruleparser%7Cmediawiki.page.ready%2Cstartup%7Cmediawiki.page.watch.ajax%7Cmediawiki.template.regexp%7Cmediawiki.widgets.CategoryMultiselectWidget%2CDateInputWidget%2CStashedFileWidget%2CUserInputWidget%2CvisibleLengthLimit%7Cmediawiki.widgets.DateInputWidget.styles%7Coojs-ui-toolbars.icons%7Coojs-ui-widgets.icons%7Coojs-ui-windows.icons%7Coojs-ui.styles.icons-content%2Cicons-editing-advanced%2Cicons-editing-citation%2Cicons-editing-core%2Cicons-editing-list%2Cicons-editing-styling%2Cicons-interactions%2Cicons-media%2Cicons-movement%7Cskins.vector.js%7Cuser.defaults%7Cwikibase.client.action.edit.collapsibleFooter&skin=vector&version=0as2p6p:223:916
resolve/</process<@https://en.wikisource.org/w/load.php?lang=en&modules=ext.CodeMirror%2CTemplateWizard%2Ccharinsert%2CeventLogging%2CnavigationTiming%2CwikimediaEvents%7Cext.CodeMirror.data%7Cext.centralNotice.geoIP%7Cext.centralauth.ForeignApi%7Cext.centralauth.centralautologin.clearcookie%7Cext.echo.api%2Cinit%7Cext.proofreadpage.icons%7Cext.proofreadpage.page.edit%2Cnavigation%7Cext.proofreadpage.ve.pageTarget.init%7Cext.uls.common%2Cinterface%2Cpreferences%2Cwebfonts%7Cext.visualEditor.desktopArticleTarget.init%7Cext.visualEditor.progressBarWidget%2CsupportCheck%2CtargetLoader%2CtempWikitextEditorWidget%2Ctrack%2Cve%7Cext.wikimediaEvents.loggedin%7Cjquery%2Cmoment%2Coojs%2Coojs-ui-core%2Coojs-ui-toolbars%2Coojs-ui-widgets%2Coojs-ui-windows%2Csite%7Cjquery.accessKeyLabel%2CcheckboxShiftClick%2Cclient%2Ccookie%2CgetAttrs%2ChighlightText%2ClengthLimit%2CmakeCollapsible%2Cmousewheel%2CprpZoom%2Csuggestions%2CtabIndex%2CtextSelection%2Cthrottle-debounce%7Cjquery.makeCollapsible.styles%7Cjquery.uls.data%7Cmediawiki.ForeignApi%2CForeignStructuredUpload%2CForeignUpload%2CRegExp%2CString%2CTitle%2CUpload%2CUri%2Capi%2Cbase%2Ccldr%2Ccookie%2Cexperiments%2Cicon%2CjqueryMsg%2Clanguage%2Cnotify%2CsearchSuggest%2Cstorage%2Ctemplate%2Cuser%2Cutil%2Cwidgets%7Cmediawiki.ForeignApi.core%7Cmediawiki.ForeignStructuredUpload.BookletLayout%7Cmediawiki.Upload.BookletLayout%2CDialog%7Cmediawiki.action.edit%7Cmediawiki.action.edit.collapsibleFooter%7Cmediawiki.language.specialCharacters%7Cmediawiki.legacy.wikibits%7Cmediawiki.libs.jpegmeta%2Cpluralruleparser%7Cmediawiki.page.ready%2Cstartup%7Cmediawiki.page.watch.ajax%7Cmediawiki.template.regexp%7Cmediawiki.widgets.CategoryMultiselectWidget%2CDateInputWidget%2CStashedFileWidget%2CUserInputWidget%2CvisibleLengthLimit%7Cmediawiki.widgets.DateInputWidget.styles%7Coojs-ui-toolbars.icons%7Coojs-ui-widgets.icons%7Coojs-ui-windows.icons%7Coojs-ui.styles.icons-content%2Cicons-editing-advanced%2Cicons-editing-citation%2Cicons-editing-core%2Cicons-editing-list%2Cicons-editing-styling%2Cicons-interactions%2Cicons-media%2Cicons-movement%7Cskins.vector.js%7Cuser.defaults%7Cwikibase.client.action.edit.collapsibleFooter&skin=vector&version=0as2p6p:224:589
undefined 2 load.php:226:749