diff --git a/React/Base/RCTAssert.h b/React/Base/RCTAssert.h
index 7914664ad..92cf1dae6 100644
--- a/React/Base/RCTAssert.h
+++ b/React/Base/RCTAssert.h
@@ -11,25 +11,10 @@
 
 #import "RCTDefines.h"
 
-/**
- * The default error domain to be used for React errors.
- */
-RCT_EXTERN NSString *const RCTErrorDomain;
-
-/**
- * A block signature to be used for custom assertion handling.
- */
-typedef void (^RCTAssertFunction)(
-  NSString *condition,
-  NSString *fileName,
-  NSNumber *lineNumber,
-  NSString *function,
-  NSString *message
-);
-
 /**
  * This is the main assert macro that you should use. Asserts should be compiled out
- * in production builds
+ * in production builds. You can customize the assert behaviour by setting a custom
+ * assert handler through `RCTSetAssertFunction`.
  */
 #ifndef NS_BLOCK_ASSERTIONS
 #define RCTAssert(condition, ...) do { \
@@ -48,21 +33,50 @@ RCT_EXTERN void _RCTAssertFormat(
   const char *, const char *, int, const char *, NSString *, ...
 ) NS_FORMAT_FUNCTION(5,6);
 
+/**
+ * Report a fatal condition when executing. These calls will _NOT_ be compiled out
+ * in production, and crash the app by default. You can customize the fatal behaviour
+ * by setting a custom fatal handler through `RCTSetFatalHandler`.
+ */
+RCT_EXTERN void RCTFatal(NSError *error);
+
+/**
+ * The default error domain to be used for React errors.
+ */
+RCT_EXTERN NSString *const RCTErrorDomain;
+
+/**
+ * JS Stack trace provided as part of an NSError's userInfo
+ */
+RCT_EXTERN NSString *const RCTJSStackTraceKey;
+
+/**
+ * A block signature to be used for custom assertion handling.
+ */
+typedef void (^RCTAssertFunction)(
+                                  NSString *condition,
+                                  NSString *fileName,
+                                  NSNumber *lineNumber,
+                                  NSString *function,
+                                  NSString *message
+                                  );
+
+typedef void (^RCTFatalHandler)(NSError *error);
+
 /**
  * Convenience macro for asserting that a parameter is non-nil/non-zero.
  */
-#define RCTAssertParam(name) RCTAssert(name, \
-@"'%s' is a required parameter", #name)
+#define RCTAssertParam(name) RCTAssert(name, @"'%s' is a required parameter", #name)
 
 /**
  * Convenience macro for asserting that we're running on main thread.
  */
 #define RCTAssertMainThread() RCTAssert([NSThread isMainThread], \
-@"This function must be called on the main thread")
+  @"This function must be called on the main thread")
 
 /**
  * These methods get and set the current assert function called by the RCTAssert
- * macros. You can use these to replace the standard behavior with custom log
+ * macros. You can use these to replace the standard behavior with custom assert
  * functionality.
  */
 RCT_EXTERN void RCTSetAssertFunction(RCTAssertFunction assertFunction);
@@ -82,6 +96,12 @@ RCT_EXTERN void RCTAddAssertFunction(RCTAssertFunction assertFunction);
  */
 RCT_EXTERN void RCTPerformBlockWithAssertFunction(void (^block)(void), RCTAssertFunction assertFunction);
 
+/**
+ These methods get and set the current fatal handler called by the RCTFatal method.
+ */
+RCT_EXTERN void RCTSetFatalHandler(RCTFatalHandler fatalHandler);
+RCT_EXTERN RCTFatalHandler RCTGetFatalHandler(void);
+
 /**
  * Get the current thread's name (or the current queue, if in debug mode)
  */
@@ -106,6 +126,6 @@ _Pragma("clang diagnostic pop")
 
 #else
 
-#define RCTAssertThread(thread, format...)
+#define RCTAssertThread(thread, format...) do { } while (0)
 
 #endif
diff --git a/React/Base/RCTAssert.m b/React/Base/RCTAssert.m
index 7d242ba9a..f28773ae5 100644
--- a/React/Base/RCTAssert.m
+++ b/React/Base/RCTAssert.m
@@ -8,12 +8,15 @@
  */
 
 #import "RCTAssert.h"
+#import "RCTLog.h"
 
 NSString *const RCTErrorDomain = @"RCTErrorDomain";
+NSString *const RCTJSStackTraceKey = @"RCTJSStackTraceKey";
 
 static NSString *const RCTAssertFunctionStack = @"RCTAssertFunctionStack";
 
 RCTAssertFunction RCTCurrentAssertFunction = nil;
+RCTFatalHandler RCTCurrentFatalHandler = nil;
 
 NSException *_RCTNotImplementedException(SEL, Class);
 NSException *_RCTNotImplementedException(SEL cmd, Class cls)
@@ -112,3 +115,44 @@ void _RCTAssertFormat(
     assertFunction(@(condition), @(fileName), @(lineNumber), @(function), message);
   }
 }
+
+void RCTFatal(NSError *error)
+{
+  _RCTLogInternal(RCTLogLevelFatal, NULL, 0, @"%@", [error localizedDescription]);
+
+  RCTFatalHandler fatalHandler = RCTGetFatalHandler();
+  if (fatalHandler) {
+    fatalHandler(error);
+  } else {
+    const NSUInteger maxMessageLength = 75;
+    NSString *message = [error localizedDescription];
+    if (message.length > maxMessageLength) {
+      message = [[message substringToIndex:maxMessageLength] stringByAppendingString:@"..."];
+    }
+
+    NSMutableString *prettyStack = [NSMutableString stringWithString:@"\n"];
+    if ([error.userInfo[RCTJSStackTraceKey] isKindOfClass:[NSArray class]]) {
+      for (NSDictionary *frame in error.userInfo[RCTJSStackTraceKey]) {
+        [prettyStack appendFormat:@"%@@%@:%@\n", frame[@"methodName"], frame[@"lineNumber"], frame[@"column"]];
+      }
+    }
+
+#if DEBUG
+    @try {
+#endif
+      [NSException raise:@"RCTFatalException" format:@"%@", message];
+#if DEBUG
+    } @catch (NSException *e) {}
+#endif
+  }
+}
+
+void RCTSetFatalHandler(RCTFatalHandler fatalhandler)
+{
+  RCTCurrentFatalHandler = fatalhandler;
+}
+
+RCTFatalHandler RCTGetFatalHandler(void)
+{
+  return RCTCurrentFatalHandler;
+}
diff --git a/React/Base/RCTBatchedBridge.m b/React/Base/RCTBatchedBridge.m
index edf436e10..2a8fcc36c 100644
--- a/React/Base/RCTBatchedBridge.m
+++ b/React/Base/RCTBatchedBridge.m
@@ -21,7 +21,6 @@
 #import "RCTModuleMap.h"
 #import "RCTPerformanceLogger.h"
 #import "RCTProfile.h"
-#import "RCTRedBox.h"
 #import "RCTSourceCode.h"
 #import "RCTSparseArray.h"
 #import "RCTUtils.h"
@@ -416,18 +415,10 @@ RCT_EXTERN NSArray<Class> *RCTGetModuleClasses(void);
 
   _loading = NO;
 
-  NSArray<NSDictionary *> *stack = error.userInfo[@"stack"];
-  if (stack) {
-    [self.redBox showErrorMessage:error.localizedDescription withStack:stack];
-  } else {
-    [self.redBox showError:error];
-  }
-  RCTLogError(@"Error while loading: %@", error.localizedDescription);
-
-  NSDictionary *userInfo = @{@"bridge": self, @"error": error};
   [[NSNotificationCenter defaultCenter] postNotificationName:RCTJavaScriptDidFailToLoadNotification
                                                       object:_parentBridge
-                                                    userInfo:userInfo];
+                                                    userInfo:@{@"bridge": self, @"error": error}];
+  RCTFatal(error);
 }
 
 RCT_NOT_IMPLEMENTED(- (instancetype)initWithBundleURL:(__unused NSURL *)bundleURL
@@ -661,7 +652,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithBundleURL:(__unused NSURL *)bundleUR
 
   RCTJavaScriptCallback processResponse = ^(id json, NSError *error) {
     if (error) {
-      [self.redBox showError:error];
+      RCTFatal(error);
     }
 
     if (!self.isValid) {
@@ -810,17 +801,23 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithBundleURL:(__unused NSURL *)bundleUR
     [method invokeWithBridge:self module:moduleData.instance arguments:params];
   }
   @catch (NSException *exception) {
-    RCTLogError(@"Exception thrown while invoking %@ on target %@ with params %@: %@", method.JSMethodName, moduleData.name, params, exception);
-    if (!RCT_DEBUG && [exception.name rangeOfString:@"Unhandled JS Exception"].location != NSNotFound) {
+    // Pass on JS exceptions
+    if ([exception.name rangeOfString:@"Unhandled JS Exception"].location == 0) {
       @throw exception;
     }
+
+    NSString *message = [NSString stringWithFormat:
+                         @"Exception thrown while invoking %@ on target %@ with params %@: %@",
+                         method.JSMethodName, moduleData.name, params, exception];
+    RCTFatal(RCTErrorWithMessage(message));
   }
 
-  NSMutableDictionary *args = [method.profileArgs mutableCopy];
-  [args setValue:method.JSMethodName forKey:@"method"];
-  [args setValue:RCTJSONStringify(RCTNullIfNil(params), NULL) forKey:@"args"];
-
-  RCTProfileEndEvent(0, @"objc_call", args);
+  if (RCTProfileIsProfiling()) {
+    NSMutableDictionary *args = [method.profileArgs mutableCopy];
+    args[@"method"] = method.JSMethodName;
+    args[@"args"] = RCTJSONStringify(RCTNullIfNil(params), NULL);
+    RCTProfileEndEvent(0, @"objc_call", args);
+  }
 
   return YES;
 }
diff --git a/React/Base/RCTBridge.m b/React/Base/RCTBridge.m
index 189cdb096..74f8b9a94 100644
--- a/React/Base/RCTBridge.m
+++ b/React/Base/RCTBridge.m
@@ -284,8 +284,9 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
 #define RCT_INNER_BRIDGE_ONLY(...) \
 - (void)__VA_ARGS__ \
 { \
-  RCTLogMustFix(@"Called method \"%@\" on top level bridge. This method should \
-              only be called from bridge instance in a bridge module", @(__func__)); \
+  NSString *errorMessage = [NSString stringWithFormat:@"Called method \"%@\" on top level bridge. \
+    This method should oly be called from bridge instance in a bridge module", @(__func__)]; \
+  RCTFatal(RCTErrorWithMessage(errorMessage)); \
 }
 
 - (void)enqueueJSCall:(NSString *)moduleDotMethod args:(NSArray *)args
diff --git a/React/Base/RCTLog.h b/React/Base/RCTLog.h
index 13bb150be..3d7670933 100644
--- a/React/Base/RCTLog.h
+++ b/React/Base/RCTLog.h
@@ -17,14 +17,9 @@
 #endif
 
 /**
- * Thresholds for logs to raise an assertion, or display redbox, respectively.
- * You can override these values when debugging in order to tweak the default
- * logging behavior.
+ * Thresholds for logs to display a redbox. You can override these values when debugging
+ * in order to tweak the default logging behavior.
  */
-#ifndef RCTLOG_FATAL_LEVEL
-#define RCTLOG_FATAL_LEVEL RCTLogLevelMustFix
-#endif
-
 #ifndef RCTLOG_REDBOX_LEVEL
 #define RCTLOG_REDBOX_LEVEL RCTLogLevelError
 #endif
@@ -37,7 +32,6 @@
 #define RCTLogInfo(...) _RCTLog(RCTLogLevelInfo, __VA_ARGS__)
 #define RCTLogWarn(...) _RCTLog(RCTLogLevelWarning, __VA_ARGS__)
 #define RCTLogError(...) _RCTLog(RCTLogLevelError, __VA_ARGS__)
-#define RCTLogMustFix(...) _RCTLog(RCTLogLevelMustFix, __VA_ARGS__)
 
 /**
  * An enum representing the severity of the log message.
@@ -46,7 +40,7 @@ typedef NS_ENUM(NSInteger, RCTLogLevel) {
   RCTLogLevelInfo = 1,
   RCTLogLevelWarning = 2,
   RCTLogLevelError = 3,
-  RCTLogLevelMustFix = 4
+  RCTLogLevelFatal = 4
 };
 
 /**
@@ -119,9 +113,7 @@ RCT_EXTERN void RCTPerformBlockWithLogPrefix(void (^block)(void), NSString *pref
  * Private logging function - ignore this.
  */
 #if RCTLOG_ENABLED
-#define _RCTLog(lvl, ...) do { \
-if (lvl >= RCTLOG_FATAL_LEVEL) { RCTAssert(NO, __VA_ARGS__); } \
-_RCTLogInternal(lvl, __FILE__, __LINE__, __VA_ARGS__); } while (0)
+#define _RCTLog(lvl, ...) _RCTLogInternal(lvl, __FILE__, __LINE__, __VA_ARGS__);
 #else
 #define _RCTLog(lvl, ...) do { } while (0)
 #endif
diff --git a/React/Base/RCTLog.m b/React/Base/RCTLog.m
index bc095afaf..b939bf8ad 100644
--- a/React/Base/RCTLog.m
+++ b/React/Base/RCTLog.m
@@ -63,7 +63,7 @@ RCTLogFunction RCTDefaultLogFunction = ^(
   fprintf(stderr, "%s\n", log.UTF8String);
   fflush(stderr);
 
-  int aslLevel = ASL_LEVEL_ERR;
+  int aslLevel;
   switch(level) {
     case RCTLogLevelInfo:
       aslLevel = ASL_LEVEL_NOTICE;
@@ -74,11 +74,9 @@ RCTLogFunction RCTDefaultLogFunction = ^(
     case RCTLogLevelError:
       aslLevel = ASL_LEVEL_ERR;
       break;
-    case RCTLogLevelMustFix:
-      aslLevel = ASL_LEVEL_EMERG;
+    case RCTLogLevelFatal:
+      aslLevel = ASL_LEVEL_CRIT;
       break;
-    default:
-      aslLevel = ASL_LEVEL_DEBUG;
   }
   asl_log(NULL, NULL, aslLevel, "%s", message.UTF8String);
 };
diff --git a/React/Base/RCTUtils.m b/React/Base/RCTUtils.m
index afc865de4..732240aec 100644
--- a/React/Base/RCTUtils.m
+++ b/React/Base/RCTUtils.m
@@ -400,8 +400,7 @@ BOOL RCTImageHasAlpha(CGImageRef image)
 NSError *RCTErrorWithMessage(NSString *message)
 {
   NSDictionary *errorInfo = @{NSLocalizedDescriptionKey: message};
-  NSError *error = [[NSError alloc] initWithDomain:RCTErrorDomain code:0 userInfo:errorInfo];
-  return error;
+  return [[NSError alloc] initWithDomain:RCTErrorDomain code:0 userInfo:errorInfo];
 }
 
 id RCTNullIfNil(id value)
diff --git a/React/Modules/RCTExceptionsManager.h b/React/Modules/RCTExceptionsManager.h
index dac22b220..20ca8d26e 100644
--- a/React/Modules/RCTExceptionsManager.h
+++ b/React/Modules/RCTExceptionsManager.h
@@ -13,16 +13,11 @@
 
 @protocol RCTExceptionsManagerDelegate <NSObject>
 
-// NOTE: Remove these three methods and the @optional directive after updating the codebase to use only the three below
+- (void)handleSoftJSExceptionWithMessage:(NSString *)message stack:(NSArray *)stack exceptionId:(NSNumber *)exceptionId;
+- (void)handleFatalJSExceptionWithMessage:(NSString *)message stack:(NSArray *)stack exceptionId:(NSNumber *)exceptionId;
+
 @optional
-
-- (void)handleSoftJSExceptionWithMessage:(NSString *)message stack:(NSArray<NSDictionary *> *)stack;
-- (void)handleFatalJSExceptionWithMessage:(NSString *)message stack:(NSArray<NSDictionary *> *)stack;
-- (void)updateJSExceptionWithMessage:(NSString *)message stack:(NSArray<NSDictionary *> *)stack;
-
-- (void)handleSoftJSExceptionWithMessage:(NSString *)message stack:(NSArray<NSDictionary *> *)stack exceptionId:(NSNumber *)exceptionId;
-- (void)handleFatalJSExceptionWithMessage:(NSString *)message stack:(NSArray<NSDictionary *> *)stack exceptionId:(NSNumber *)exceptionId;
-- (void)updateJSExceptionWithMessage:(NSString *)message stack:(NSArray<NSDictionary *> *)stack exceptionId:(NSNumber *)exceptionId;
+- (void)updateJSExceptionWithMessage:(NSString *)message stack:(NSArray *)stack exceptionId:(NSNumber *)exceptionId;
 
 @end
 
diff --git a/React/Modules/RCTExceptionsManager.m b/React/Modules/RCTExceptionsManager.m
index 17a713e8e..9cc5d5722 100644
--- a/React/Modules/RCTExceptionsManager.m
+++ b/React/Modules/RCTExceptionsManager.m
@@ -43,58 +43,31 @@ RCT_EXPORT_METHOD(reportSoftException:(NSString *)message
                   stack:(NSDictionaryArray *)stack
                   exceptionId:(nonnull NSNumber *)exceptionId)
 {
-  // TODO(#7070533): report a soft error to the server
-  if (_delegate) {
-    if ([_delegate respondsToSelector:@selector(handleSoftJSExceptionWithMessage:stack:exceptionId:)]) {
-      [_delegate handleSoftJSExceptionWithMessage:message stack:stack exceptionId:exceptionId];
-    } else {
-      [_delegate handleSoftJSExceptionWithMessage:message stack:stack];
-    }
-    return;
-  }
   [_bridge.redBox showErrorMessage:message withStack:stack];
+
+  if (_delegate) {
+    [_delegate handleSoftJSExceptionWithMessage:message stack:stack exceptionId:exceptionId];
+  }
 }
 
 RCT_EXPORT_METHOD(reportFatalException:(NSString *)message
                   stack:(NSDictionaryArray *)stack
                   exceptionId:(nonnull NSNumber *)exceptionId)
 {
-  if (_delegate) {
-    if ([_delegate respondsToSelector:@selector(handleFatalJSExceptionWithMessage:stack:exceptionId:)]) {
-      [_delegate handleFatalJSExceptionWithMessage:message stack:stack exceptionId:exceptionId];
-    } else {
-      [_delegate handleFatalJSExceptionWithMessage:message stack:stack];
-    }
-    return;
-  }
-
   [_bridge.redBox showErrorMessage:message withStack:stack];
 
-  if (!RCT_DEBUG) {
+  if (_delegate) {
+    [_delegate handleFatalJSExceptionWithMessage:message stack:stack exceptionId:exceptionId];
+  }
 
-    static NSUInteger reloadRetries = 0;
-    const NSUInteger maxMessageLength = 75;
-
-    if (reloadRetries < _maxReloadAttempts) {
-
-      reloadRetries++;
-      [[NSNotificationCenter defaultCenter] postNotificationName:RCTReloadNotification
-                                                          object:nil];
-
-    } else {
-
-      if (message.length > maxMessageLength) {
-        message = [[message substringToIndex:maxMessageLength] stringByAppendingString:@"..."];
-      }
-
-      NSMutableString *prettyStack = [NSMutableString stringWithString:@"\n"];
-      for (NSDictionary *frame in stack) {
-        [prettyStack appendFormat:@"%@@%@:%@\n", frame[@"methodName"], frame[@"lineNumber"], frame[@"column"]];
-      }
-
-      NSString *name = [@"Unhandled JS Exception: " stringByAppendingString:message];
-      [NSException raise:name format:@"Message: %@, stack: %@", message, prettyStack];
-    }
+  static NSUInteger reloadRetries = 0;
+  if (!RCT_DEBUG && reloadRetries < _maxReloadAttempts) {
+    reloadRetries++;
+    [[NSNotificationCenter defaultCenter] postNotificationName:RCTReloadNotification object:nil];
+  } else {
+    NSString *description = [@"Unhandled JS Exception: " stringByAppendingString:message];
+    NSDictionary *errorInfo = @{ NSLocalizedDescriptionKey: description, RCTJSStackTraceKey: stack };
+    RCTFatal([NSError errorWithDomain:RCTErrorDomain code:0 userInfo:errorInfo]);
   }
 }
 
@@ -102,16 +75,11 @@ RCT_EXPORT_METHOD(updateExceptionMessage:(NSString *)message
                   stack:(NSDictionaryArray *)stack
                   exceptionId:(nonnull NSNumber *)exceptionId)
 {
-  if (_delegate) {
-    if ([_delegate respondsToSelector:@selector(updateJSExceptionWithMessage:stack:exceptionId:)]) {
-      [_delegate updateJSExceptionWithMessage:message stack:stack exceptionId:exceptionId];
-    } else {
-      [_delegate updateJSExceptionWithMessage:message stack:stack];
-    }
-    return;
-  }
-
   [_bridge.redBox updateErrorMessage:message withStack:stack];
+
+  if (_delegate && [_delegate respondsToSelector:@selector(updateJSExceptionWithMessage:stack:exceptionId:)]) {
+    [_delegate updateJSExceptionWithMessage:message stack:stack exceptionId:exceptionId];
+  }
 }
 
 // Deprecated.  Use reportFatalException directly instead.
@@ -120,4 +88,5 @@ RCT_EXPORT_METHOD(reportUnhandledException:(NSString *)message
 {
   [self reportFatalException:message stack:stack exceptionId:@-1];
 }
+
 @end
diff --git a/React/Modules/RCTUIManager.m b/React/Modules/RCTUIManager.m
index 6c7e500a4..44ac329e3 100644
--- a/React/Modules/RCTUIManager.m
+++ b/React/Modules/RCTUIManager.m
@@ -647,8 +647,9 @@ RCT_EXPORT_METHOD(removeSubviewsFromContainerWithID:(nonnull NSNumber *)containe
     }
   }
   if (removedChildren.count != atIndices.count) {
-    RCTLogMustFix(@"removedChildren count (%tu) was not what we expected (%tu)",
-                  removedChildren.count, atIndices.count);
+    NSString *message = [NSString stringWithFormat:@"removedChildren count (%tu) was not what we expected (%tu)",
+                         removedChildren.count, atIndices.count];
+    RCTFatal(RCTErrorWithMessage(message));
   }
   return removedChildren;
 }