diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java
index 4c45be94b17..0d608768561 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java
@@ -1286,6 +1286,7 @@ public class DefaultCodegen implements CodegenConfig {
 
     /**
      * Return property value depending on property type.
+     *
      * @param schema property type
      * @return property value
      */
@@ -1450,7 +1451,8 @@ public class DefaultCodegen implements CodegenConfig {
             } else if (ModelUtils.isDoubleSchema(schema)) {
                 return SchemaTypeUtil.DOUBLE_FORMAT;
             } else {
-                LOGGER.warn("Unknown `format` detected for " + schema.getName() + ": " + schema.getFormat());
+                LOGGER.warn("Unknown `format` {} detected for type `number`. Defaulting to `number`", schema.getFormat());
+                return "number";
             }
         } else if (ModelUtils.isIntegerSchema(schema)) {
             if (ModelUtils.isLongSchema(schema)) {
@@ -1891,7 +1893,7 @@ public class DefaultCodegen implements CodegenConfig {
      */
     public CodegenProperty fromProperty(String name, Schema p) {
         if (p == null) {
-            LOGGER.error("Undefined property/schema for `{}`. Default to type:string.",  name);
+            LOGGER.error("Undefined property/schema for `{}`. Default to type:string.", name);
             return null;
         }
         LOGGER.debug("debugging fromProperty for " + name + " : " + p);
@@ -2041,7 +2043,7 @@ public class DefaultCodegen implements CodegenConfig {
             if (innerSchema == null) {
                 LOGGER.error("Undefined array inner type for `{}`. Default to String.", p.getName());
                 innerSchema = new StringSchema().description("//TODO automatically added by openapi-generator due to undefined type");
-                ((ArraySchema)p).setItems(innerSchema);
+                ((ArraySchema) p).setItems(innerSchema);
             }
         } else if (ModelUtils.isMapSchema(p)) {
             Schema innerSchema = ModelUtils.unaliasSchema(this.openAPI, ModelUtils.getAdditionalProperties(p));
@@ -2123,7 +2125,7 @@ public class DefaultCodegen implements CodegenConfig {
             if (innerSchema == null) {
                 LOGGER.error("Undefined array inner type for `{}`. Default to String.", p.getName());
                 innerSchema = new StringSchema().description("//TODO automatically added by openapi-generator due to undefined type");
-                ((ArraySchema)p).setItems(innerSchema);
+                ((ArraySchema) p).setItems(innerSchema);
             }
             CodegenProperty cp = fromProperty(itemName, innerSchema);
             updatePropertyForArray(property, cp);
@@ -2515,8 +2517,8 @@ public class DefaultCodegen implements CodegenConfig {
         CodegenParameter bodyParam = null;
         RequestBody requestBody = operation.getRequestBody();
         if (requestBody != null) {
-            if ("application/x-www-form-urlencoded".equalsIgnoreCase(getContentType(requestBody)) ||
-                    "multipart/form-data".equalsIgnoreCase(getContentType(requestBody))) {
+            if (getContentType(requestBody).toLowerCase(Locale.ROOT).startsWith("application/x-www-form-urlencoded") ||
+                    getContentType(requestBody).toLowerCase(Locale.ROOT).startsWith("multipart/form-data")) {
                 // process form parameters
                 formParams = fromRequestBodyToFormParameters(requestBody, imports);
                 for (CodegenParameter cp : formParams) {
@@ -4194,7 +4196,8 @@ public class DefaultCodegen implements CodegenConfig {
 
     protected String getContentType(RequestBody requestBody) {
         if (requestBody == null || requestBody.getContent() == null || requestBody.getContent().isEmpty()) {
-            return null;
+            LOGGER.warn("Cannot determine the content type. Default to UNKNOWN_CONTENT_TYPE.");
+            return "UNKNOWN_CONTENT_TYPE";
         }
         return new ArrayList<>(requestBody.getContent().keySet()).get(0);
     }
@@ -4275,7 +4278,9 @@ public class DefaultCodegen implements CodegenConfig {
         }
 
         for (String consume : consumesInfo) {
-            if ("application/x-www-form-urlencoded".equalsIgnoreCase(consume) || "multipart/form-data".equalsIgnoreCase(consume)) {
+            if (consume != null &&
+                    consume.toLowerCase(Locale.ROOT).startsWith("application/x-www-form-urlencoded") ||
+                    consume.toLowerCase(Locale.ROOT).startsWith("multipart/form-data")) {
                 return true;
             }
         }
@@ -4849,7 +4854,7 @@ public class DefaultCodegen implements CodegenConfig {
     }
 
     private void setParameterNullable(CodegenParameter parameter, CodegenProperty property) {
-        if(parameter == null || property == null) {
+        if (parameter == null || property == null) {
             return;
         }
         parameter.isNullable = property.isNullable;
@@ -4898,7 +4903,7 @@ public class DefaultCodegen implements CodegenConfig {
     /**
      * Set the boolean value indicating the state of the option for updating only changed files
      *
-     * @param enableMinimalUpdate    true to enable minimal update
+     * @param enableMinimalUpdate true to enable minimal update
      */
     @Override
     public void setEnableMinimalUpdate(boolean enableMinimalUpdate) {