FATAL: sorry, too many clients already

  "browser-info": {
    "language": "pt-BR",
    "platform": "Linux x86_64",
    "userAgent": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/90.0.4430.212 Safari/537.36",
    "vendor": "Google Inc."
  "system-info": {
    "file.encoding": "UTF-8",
    "java.runtime.name": "OpenJDK Runtime Environment",
    "java.runtime.version": "11.0.7+10",
    "java.vendor": "AdoptOpenJDK",
    "java.vendor.url": "https://adoptopenjdk.net/",
    "java.version": "11.0.7",
    "java.vm.name": "OpenJDK 64-Bit Server VM",
    "java.vm.version": "11.0.7+10",
    "os.name": "Linux",
    "os.version": "5.4.0-1051-azure",
    "user.language": "en",
    "user.timezone": "GMT"
  "metabase-info": {
    "databases": [
    "hosting-env": "unknown",
    "application-database": "h2",
    "application-database-details": {
      "database": {
        "name": "H2",
        "version": "1.4.197 (2018-03-18)"
      "jdbc-driver": {
        "name": "H2 JDBC Driver",
        "version": "1.4.197 (2018-03-18)"
    "run-mode": "prod",
    "version": {
      "date": "2021-04-08",
      "tag": "v0.38.4",
      "branch": "release-x.38.x",
      "hash": "057b6bb"
    "settings": {
      "report-timezone": "America/Sao_Paulo"

Hi @jefferson.araujo
Since you're providing no information, then it's impossible to help, but have a look here:
Then upgrade to the latest release:
And then migrate away from H2:

Thank you for the informations. The problem ended up being solved with the new versions.

Thanks for the database tip, I'll prepare this migration.