414 Request-URI Too Large even after changing MB_JETTY_REQUEST_HEADER_SIZE

Problem: I'm using Metabase embedded with locked parameters. When the list of parameters is super large, the url (src of the iframe) is huge, (8600 characters) and I get a "414 Request-URI Too Large" error.

What have I tried:

  • I set MB_JETTY_REQUEST_HEADER_SIZE=100000. In the logs, I can see the following:
[c0b46dc9-7b8f-4dbc-b2bb-91405eb99731] 2023-04-05T17:53:44-03:00 INFO metabase.server Launching Embedded Jetty Webserver with config: 
 {:port 3000, :host "", :request-header-size 100000}
  • I made a POST request to the url instead of a GET request. Same problem.

  • When the number of parameters is small, it works normally.

Diagnostic info:

  "browser-info": {
    "language": "en-US",
    "platform": "Win32",
    "userAgent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:109.0) Gecko/20100101 Firefox/111.0",
    "vendor": ""
  "system-info": {
    "file.encoding": "UTF-8",
    "java.runtime.name": "OpenJDK Runtime Environment",
    "java.runtime.version": "11.0.18+10",
    "java.vendor": "Eclipse Adoptium",
    "java.vendor.url": "https://adoptium.net/",
    "java.version": "11.0.18",
    "java.vm.name": "OpenJDK 64-Bit Server VM",
    "java.vm.version": "11.0.18+10",
    "os.name": "Linux",
    "os.version": "4.14.305-227.531.amzn2.x86_64",
    "user.language": "en",
    "user.timezone": "GMT"
  "metabase-info": {
    "databases": [
    "hosting-env": "unknown",
    "application-database": "postgres",
    "application-database-details": {
      "database": {
        "name": "PostgreSQL",
        "version": "13.7"
      "jdbc-driver": {
        "name": "PostgreSQL JDBC Driver",
        "version": "42.5.1"
    "run-mode": "prod",
    "version": {
      "date": "2023-03-28",
      "tag": "v0.46.0",
      "branch": "release-x.46.x",
      "hash": "0ca7df3"
    "settings": {
      "report-timezone": "Etc/GMT+0"

Is there anything else I can try?

this is weird, as the env var should work without any problem. Can you increase it even further just to test?