The moment you try to perform a language check after activating the en n-gram data set:
Jan 27 11:49:49 2023-01-27 10:49:49 +0000 Starting LanguageTool 6.0 (build date: 2022-12-29 12:13:11 +0000, e44dbb0) server on http://localhost:8010...
Jan 27 11:49:49 2023-01-27 10:49:49 +0000 Server started
Jan 27 11:49:50 172.18.0.1 - - [27/Jan/2023:10:49:50 +0000] "GET / HTTP/1.1" 200 810 "-" "Mozilla (CloudronHealth)"
Jan 27 11:50:00 172.18.0.1 - - [27/Jan/2023:10:50:00 +0000] "GET / HTTP/1.1" 200 810 "-" "Mozilla (CloudronHealth)"
Jan 27 11:50:10 172.18.0.1 - - [27/Jan/2023:10:50:10 +0000] "GET / HTTP/1.1" 200 810 "-" "Mozilla (CloudronHealth)"
Jan 27 11:50:12 2023-01-27 10:50:12.527 +0000 INFO org.languagetool.server.LanguageToolHttpHandler Handling POST /v2/check
Jan 27 11:50:12 2023-01-27 10:50:12.527 +0000 INFO org.languagetool.server.LanguageToolHttpHandler Handling POST /v2/check
Jan 27 11:50:15 2023-01-27 10:50:15.099 +0000 ERROR org.languagetool.server.LanguageToolHttpHandler An error has occurred: 'java.lang.RuntimeException: Expected at least '1grams', '2grams', and '3grams' sub directories but only got [3grams] in /app/data/ngrams/en, detected: en-US', sending HTTP code 500. Access from 0:0:0:0:0:0:0:1, HTTP user agent: Mozilla/5.0 (X11; Linux x86_64; rv:109.0) Gecko/20100101 Firefox/109.0, User agent param: webextension-firefox-ng, v: 6.0.1, Referrer: null, language: en-gb, h: 2, r: 2, time: 2589m: TEXTLEVEL_ONLY, l: PICKY, iID: 94148:1674816428889, Stacktrace follows:java.lang.RuntimeException: java.lang.RuntimeException: Expected at least '1grams', '2grams', and '3grams' sub directories but only got [3grams] in /app/data/ngrams/en, detected: en-US
Jan 27 11:50:15 at org.languagetool.server.TextChecker.checkText(TextChecker.java:507)
Jan 27 11:50:15 at org.languagetool.server.ApiV2.handleCheckRequest(ApiV2.java:172)
Jan 27 11:50:15 at org.languagetool.server.ApiV2.handleRequest(ApiV2.java:83)
Jan 27 11:50:15 at org.languagetool.server.LanguageToolHttpHandler.handle(LanguageToolHttpHandler.java:185)
Jan 27 11:50:15 at jdk.httpserver/com.sun.net.httpserver.Filter$Chain.doFilter(Filter.java:77)
Jan 27 11:50:15 at jdk.httpserver/sun.net.httpserver.AuthFilter.doFilter(AuthFilter.java:82)
Jan 27 11:50:15 at jdk.httpserver/com.sun.net.httpserver.Filter$Chain.doFilter(Filter.java:80)
Jan 27 11:50:15 at jdk.httpserver/sun.net.httpserver.ServerImpl$Exchange$LinkHandler.handle(ServerImpl.java:848)
Jan 27 11:50:15 at jdk.httpserver/com.sun.net.httpserver.Filter$Chain.doFilter(Filter.java:77)
Jan 27 11:50:15 at jdk.httpserver/sun.net.httpserver.ServerImpl$Exchange.run(ServerImpl.java:817)
Jan 27 11:50:15 at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
Jan 27 11:50:15 at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
Jan 27 11:50:15 at java.base/java.lang.Thread.run(Thread.java:829)
Jan 27 11:50:15 Caused by: java.util.concurrent.ExecutionException: java.lang.RuntimeException: Expected at least '1grams', '2grams', and '3grams' sub directories but only got [3grams] in /app/data/ngrams/en
Jan 27 11:50:15 at java.base/java.util.concurrent.FutureTask.report(FutureTask.java:122)
Jan 27 11:50:15 at java.base/java.util.concurrent.FutureTask.get(FutureTask.java:191)
Jan 27 11:50:15 at org.languagetool.server.TextChecker.checkText(TextChecker.java:489)
Jan 27 11:50:15 ... 12 more
Jan 27 11:50:15 Caused by: java.lang.RuntimeException: Expected at least '1grams', '2grams', and '3grams' sub directories but only got [3grams] in /app/data/ngrams/en
Jan 27 11:50:15 at org.languagetool.languagemodel.LuceneSingleIndexLanguageModel.validateDirectory(LuceneSingleIndexLanguageModel.java:72)
Jan 27 11:50:15 at org.languagetool.languagemodel.LuceneSingleIndexLanguageModel.doValidateDirectory(LuceneSingleIndexLanguageModel.java:109)