{"record":{"id":"4e29895806acc136","repo":"pentaho/pentaho-kettle","slug":"dynamic-driver-effectiveclassname-returned-null-for-url-url","errorCode":null,"errorMessage":"Dynamic driver '{effectiveClassName}' returned null for URL: {url} — check that the URL format and driver class are correct.","messagePattern":"Dynamic driver '(.+?)' returned null for URL: (.+?) — check that the URL format and driver class are correct\\.","errorType":"exception","errorClass":"KettleDatabaseException","httpStatus":null,"severity":"error","filePath":"core/src/main/java/org/pentaho/di/core/database/Database.java","lineNumber":959,"sourceCode":"          + \"Reconnect to reload the driver.\" );\n    }\n    boolean accepts;\n    try {\n      accepts = localDriver.acceptsURL( url );\n    } catch ( Exception e ) {\n      throw new KettleDatabaseException(\n        \"Dynamic driver '\" + effectiveClassName + \"' threw exception checking URL '\"\n          + url + \"': \" + errorMsg( e ), e );\n    }\n    if ( !accepts ) {\n      throw new KettleDatabaseException(\n        \"Dynamic driver '\" + effectiveClassName + \"' does not accept URL: \" + url\n          + \" — check the JDBC URL format.\" );\n    }\n    try {\n      Connection c = localDriver.connect( url, properties );\n      if ( c == null ) {\n        throw new KettleDatabaseException(\n          \"Dynamic driver '\" + effectiveClassName + \"' returned null for URL: \" + url\n            + \" — check that the URL format and driver class are correct.\" );\n      }\n      return c;\n    } catch ( KettleDatabaseException e ) {\n      throw e;\n    } catch ( Exception e ) {\n      throw new KettleDatabaseException(\n        \"Dynamic driver '\" + effectiveClassName + \"' failed to connect to URL '\"\n          + url + \"': \" + errorMsg( e ), e );\n    }\n  }\n\n  /**\n   * Returns the exception message, or the simple class name when the message is null.\n   * Avoids repetitive inline ternary expressions in error-handling code.\n   */\n  private static String errorMsg( Exception e ) {","sourceCodeStart":941,"sourceCodeEnd":977,"githubUrl":"https://github.com/pentaho/pentaho-kettle/blob/f3058517a153da500bf4551f46d79b91bf8ec552/core/src/main/java/org/pentaho/di/core/database/Database.java#L941-L977","documentation":"Per the JDBC spec, Driver.connect may legally return null to signal 'this driver cannot connect to this URL'. PDI treats that null as a fatal, descriptive error because the driver already claimed to accept the URL, so a null is unexpected and usually indicates a wrong driver class or subtly wrong URL.","triggerScenarios":"connectUsingClass -> openConnectionViaDynamicDriver: localDriver.acceptsURL(url) returned true but localDriver.connect(url, properties) returned null — driver changed its mind due to URL details, properties mismatch, or a shim/wrapper driver that delegates to nothing.","commonSituations":"Driver class mismatch with the actual database (thin vs shim driver); URL accepted at prefix level but rejected on deeper validation; missing/incorrect connection properties the driver requires; stale/wrong driver version.","solutions":["Confirm the driver class actually corresponds to the database in the URL","Check the JDBC URL format against the vendor docs (prefix acceptance is shallower than connect)","Supply required connection Properties (user, password, database name)","Try a current, official driver JAR version"],"exampleFix":"// before\nprops = new Properties(); // no user/password -> driver returns null\n// after\nprops.setProperty(\"user\", \"scott\");\nprops.setProperty(\"password\", \"tiger\");","handlingStrategy":"validation","validationCode":"Properties p = new Properties();\np.setProperty(\"user\", user); p.setProperty(\"password\", pwd);\nif (url == null || !url.startsWith(\"jdbc:\")) throw new IllegalArgumentException(\"Malformed JDBC URL\");","typeGuard":null,"tryCatchPattern":"try { conn = db.getConnection(); } catch (KettleDatabaseException e) { if (e.getMessage().contains(\"returned null for URL\")) { log.error(\"Driver silently refused URL — verify class/URL/properties: \" + e.getMessage()); } else throw e; }","preventionTips":["Always supply required connection properties (user/password/database)","Confirm the driver class matches the database product and version","Test the same URL+properties with a standalone JDBC snippet","Keep drivers updated to current vendor releases"],"tags":["jdbc","url","dynamic-driver","connection"],"backgroundTag":"invalid-url-format","analyzedSha":"f3058517a153da500bf4551f46d79b91bf8ec552","analyzedAt":"2026-09-13T14:04:16.340Z","contentChangedAt":"2026-09-13T14:04:16.340Z","schemaVersion":2},"datasetVersion":"2026-09-20T23:17:15.980Z"}