diff --git a/builtins/append.go b/builtins/append.go
index a4d867b9..92bc0711 100644
--- a/builtins/append.go
+++ b/builtins/append.go
@@ -57,7 +57,7 @@ func Append(s *symbols.SymbolTable, args data.List) (interface{}, error) {
 				// appropriate type.
 				if typeChecking > defs.StrictTypeEnforcement {
 					if j, err = data.Coerce(j, data.InstanceOfType(kind)); err != nil {
-						return nil, err
+						return nil, errors.New(err).In("append")
 					}
 				} else {
 					// Nope, we are in strict type checking mode, so complain and be done.
diff --git a/builtins/cast.go b/builtins/cast.go
index e60814b0..20c508d4 100644
--- a/builtins/cast.go
+++ b/builtins/cast.go
@@ -52,7 +52,7 @@ func Cast(s *symbols.SymbolTable, args data.List) (interface{}, error) {
 
 			value, err := data.Coerce(source, data.InstanceOfType(t.BaseType()))
 			if err != nil {
-				return nil, err
+				return nil, errors.New(err).In(t.BaseType().String())
 			}
 
 			_ = r.Set(0, value)
@@ -62,7 +62,7 @@ func Cast(s *symbols.SymbolTable, args data.List) (interface{}, error) {
 
 		v, err := data.Coerce(source, data.InstanceOfType(t))
 		if err != nil {
-			return nil, err
+			return nil, errors.New(err).In(t.String())
 		}
 
 		if v != nil {
diff --git a/bytecode/coerce.go b/bytecode/coerce.go
index 206da3ca..4dcc16f0 100644
--- a/bytecode/coerce.go
+++ b/bytecode/coerce.go
@@ -109,9 +109,9 @@ func coerceByteCode(c *Context, i interface{}) error {
 		for i, element := range base {
 			v, err := data.Coerce(element, model)
 			if err != nil {
-				return err
+				return c.error(err)
 			}
-			
+
 			_ = array.Set(i, v)
 		}
 
diff --git a/bytecode/context.go b/bytecode/context.go
index 7bae4561..bf574e09 100644
--- a/bytecode/context.go
+++ b/bytecode/context.go
@@ -492,14 +492,14 @@ func (c *Context) checkType(name string, value interface{}) (interface{}, error)
 			if newT.IsIntegerType() && oldT.IsIntegerType() {
 				value, err = data.Coerce(value, existingValue)
 				if err != nil {
-					return nil, err
+					return nil, c.error(err)
 				}
 			}
 
 			if newT.IsFloatType() && oldT.IsFloatType() {
 				value, err = data.Coerce(value, existingValue)
 				if err != nil {
-					return nil, err
+					return nil, c.error(err)
 				}
 			}
 		} else if c.typeStrictness == defs.StrictTypeEnforcement && canCoerce {
@@ -511,7 +511,7 @@ func (c *Context) checkType(name string, value interface{}) (interface{}, error)
 			if ok && (oldT.IsIntegerType() || oldT.IsFloatType()) {
 				value, err = data.Coerce(value, existingValue)
 				if err != nil {
-					return nil, err
+					return nil, c.error(err)
 				}
 			}
 
diff --git a/bytecode/create.go b/bytecode/create.go
index d2f4f0bc..e9014aac 100644
--- a/bytecode/create.go
+++ b/bytecode/create.go
@@ -336,7 +336,7 @@ func applyStructModel(c *Context, model interface{}, structMap map[string]interf
 		// by chasing the model chain.
 		err := addMissingFields(model, structMap, c)
 		if err != nil {
-			return nil, err
+			return nil, c.error(err)
 		}
 	} else {
 		return nil, c.error(errors.ErrUnknownType, typeInfo.String())
@@ -370,7 +370,7 @@ func addMissingFields(model *data.Struct, structMap map[string]interface{}, c *C
 						if err == nil {
 							return err
 						}
-						
+
 						structMap[fieldName] = existingValue
 					} else {
 						typeString := data.TypeOf(existingValue).String()
diff --git a/bytecode/math.go b/bytecode/math.go
index 219e4b8b..214eeff2 100644
--- a/bytecode/math.go
+++ b/bytecode/math.go
@@ -59,7 +59,7 @@ func incrementByteCode(c *Context, i interface{}) error {
 			if a.Type().BaseType().Kind() != data.InterfaceType.Kind() {
 				increment, err = data.Coerce(increment, data.InstanceOfType(a.Type().BaseType()))
 				if err != nil {
-					return err
+					return c.error(err)
 				}
 			}
 		}
@@ -282,7 +282,7 @@ func addByteCode(c *Context, i interface{}) error {
 		if _, ok := v2.(*data.Array); !ok && c.typeStrictness != defs.StrictTypeEnforcement {
 			v2, err = data.Coerce(v2, data.InstanceOfType(a.Type().BaseType()))
 			if err != nil {
-				return err
+				return c.error(err)
 			}
 		}
 
@@ -298,7 +298,7 @@ func addByteCode(c *Context, i interface{}) error {
 		if _, ok := v1.(*data.Array); !ok && c.typeStrictness != defs.StrictTypeEnforcement {
 			v1, err = data.Coerce(v1, data.InstanceOfType(a.Type().BaseType()))
 			if err != nil {
-				return err
+				return c.error(err)
 			}
 		}
 
diff --git a/bytecode/store.go b/bytecode/store.go
index c1076718..c02c8614 100644
--- a/bytecode/store.go
+++ b/bytecode/store.go
@@ -320,7 +320,7 @@ func storeStringViaPointer(c *Context, name string, src interface{}, destination
 	if c.typeStrictness > defs.RelaxedTypeEnforcement {
 		d, err = data.Coerce(src, "")
 		if err != nil {
-			return err
+			return c.error(err)
 		}
 	} else if _, ok := d.(string); !ok {
 		return c.error(errors.ErrInvalidVarType).Context(name)
@@ -338,7 +338,7 @@ func storeFloat32ViaPointer(c *Context, name string, src interface{}, destinatio
 	if c.typeStrictness > defs.RelaxedTypeEnforcement {
 		d, err = data.Coerce(src, float32(0))
 		if err != nil {
-			return err
+			return c.error(err)
 		}
 	} else if _, ok := d.(string); !ok {
 		return c.error(errors.ErrInvalidVarType).Context(name)
@@ -356,7 +356,7 @@ func storeFloat64ViaPointer(c *Context, name string, src interface{}, destinatio
 	if c.typeStrictness > defs.RelaxedTypeEnforcement {
 		d, err = data.Coerce(src, float64(0))
 		if err != nil {
-			return err
+			return c.error(err)
 		}
 	} else if _, ok := d.(string); !ok {
 		return c.error(errors.ErrInvalidVarType).Context(name)
@@ -374,7 +374,7 @@ func storeInt64ViaPointer(c *Context, name string, src interface{}, actual *int6
 	if c.typeStrictness > defs.RelaxedTypeEnforcement {
 		d, err = data.Coerce(src, int64(1))
 		if err != nil {
-			return err
+			return c.error(err)
 		}
 	} else if _, ok := d.(string); !ok {
 		return c.error(errors.ErrInvalidVarType).Context(name)
@@ -392,7 +392,7 @@ func storeIntViaPointer(c *Context, name string, src interface{}, actual *int) e
 	if c.typeStrictness > defs.RelaxedTypeEnforcement {
 		d, err = data.Coerce(src, int(1))
 		if err != nil {
-			return err
+			return c.error(err)
 		}
 	} else if _, ok := d.(string); !ok {
 		return c.error(errors.ErrInvalidVarType).Context(name)
@@ -410,7 +410,7 @@ func storeInt32ViaPointer(c *Context, name string, src interface{}, actual *int3
 	if c.typeStrictness > defs.RelaxedTypeEnforcement {
 		d, err = data.Coerce(src, int32(1))
 		if err != nil {
-			return err
+			return c.error(err)
 		}
 	} else if _, ok := d.(string); !ok {
 		return c.error(errors.ErrInvalidVarType).Context(name)
@@ -428,7 +428,7 @@ func storeByteViaPointer(c *Context, name string, src interface{}, actual *byte)
 	if c.typeStrictness > defs.RelaxedTypeEnforcement {
 		d, err = data.Coerce(src, byte(1))
 		if err != nil {
-			return err
+			return c.error(err)
 		}
 	} else if _, ok := d.(string); !ok {
 		return c.error(errors.ErrInvalidVarType).Context(name)
@@ -446,7 +446,7 @@ func storeBoolViaPointer(c *Context, name string, src interface{}, actual *bool)
 	if c.typeStrictness > defs.RelaxedTypeEnforcement {
 		d, err = data.Coerce(src, true)
 		if err != nil {
-			return err
+			return c.error(err)
 		}
 	} else if _, ok := d.(string); !ok {
 		return c.error(errors.ErrInvalidVarType).Context(name)
@@ -475,7 +475,7 @@ func storeAlwaysByteCode(c *Context, i interface{}) error {
 
 		v, err = c.Pop()
 		if err != nil {
-			return err
+			return c.error(err)
 		}
 
 		if isStackMarker(v) {
diff --git a/bytecode/types.go b/bytecode/types.go
index 7a6cc2ae..a6a7ab48 100644
--- a/bytecode/types.go
+++ b/bytecode/types.go
@@ -98,7 +98,7 @@ func unwrapByteCode(c *Context, i interface{}) error {
 	if c.typeStrictness != defs.StrictTypeEnforcement {
 		newValue, err = data.Coerce(value, newType.InstanceOf(newType.BaseType()))
 		if err != nil {
-			return err
+			return c.error(err)
 		}
 	} else {
 		if !actualType.IsType(newType) {
diff --git a/data/coerce.go b/data/coerce.go
index 761895be..c82efdd7 100644
--- a/data/coerce.go
+++ b/data/coerce.go
@@ -251,7 +251,7 @@ func coerceToInt(v interface{}) (interface{}, error) {
 
 		st, err := strconv.Atoi(value)
 		if err != nil {
-			return nil, err
+			return nil, errors.ErrInvalidInteger.Context(value)
 		}
 
 		return st, nil
@@ -297,7 +297,7 @@ func coerceToInt64(v interface{}) (interface{}, error) {
 
 		st, err := strconv.Atoi(value)
 		if err != nil {
-			return nil, err
+			return nil, errors.ErrInvalidInteger.Context(value)
 		}
 
 		return int64(st), nil
@@ -358,7 +358,7 @@ func coerceInt32(v interface{}) (interface{}, error) {
 
 		intValue, err := strconv.Atoi(value)
 		if err != nil {
-			return nil, err
+			return nil, errors.ErrInvalidInteger.Context(value)
 		}
 
 		return coerceInt32(intValue)
@@ -429,7 +429,7 @@ func coerceToByte(v interface{}) (interface{}, error) {
 
 		st, err := strconv.Atoi(value)
 		if err != nil {
-			return nil, err
+			return nil, errors.ErrInvalidInteger.Context(value)
 		}
 
 		return coerceToByte(st)
diff --git a/debugger/breaks.go b/debugger/breaks.go
index 85cebb09..6a2342b1 100644
--- a/debugger/breaks.go
+++ b/debugger/breaks.go
@@ -104,7 +104,7 @@ func breakCommand(t *tokenizer.Tokenizer) error {
 					err = breakAtLine(name, line)
 				}
 			} else {
-				err = errors.New(e2)
+				err = errors.New(errors.ErrInvalidInteger)
 			}
 
 			clauses++
diff --git a/debugger/show.go b/debugger/show.go
index a0b13e92..009f46b2 100644
--- a/debugger/show.go
+++ b/debugger/show.go
@@ -55,7 +55,7 @@ func showCommand(s *symbols.SymbolTable, tokens *tokenizer.Tokenizer, line int,
 
 				depth, e2 = strconv.Atoi(tx.Spelling())
 				if e2 != nil {
-					err = errors.New(e2)
+					err = errors.ErrInvalidInteger
 				}
 			}
 		}
diff --git a/debugger/source.go b/debugger/source.go
index 74cb42dc..29b66329 100644
--- a/debugger/source.go
+++ b/debugger/source.go
@@ -29,7 +29,7 @@ func showSource(tx *tokenizer.Tokenizer, tokens *tokenizer.Tokenizer, err error)
 		}
 
 		if e2 != nil {
-			err = errors.New(e2)
+			err = errors.New(errors.ErrInvalidInteger)
 		}
 	}
 
diff --git a/errors/messages.go b/errors/messages.go
index dbdada2d..909e6448 100644
--- a/errors/messages.go
+++ b/errors/messages.go
@@ -81,7 +81,7 @@ var ErrInvalidFunctionName = Message("func.name")
 var ErrInvalidIdentifier = Message("identifier")
 var ErrInvalidImport = Message("import")
 var ErrInvalidInstruction = Message("instruction")
-var ErrInvalidInteger = Message("integer.option")
+var ErrInvalidInteger = Message("integer.value")
 var ErrInvalidKeyword = Message("keyword.option")
 var ErrInvalidLineNumber = Message("line.number")
 var ErrInvalidList = Message("list")
diff --git a/i18n/languages/messages_en.txt b/i18n/languages/messages_en.txt
index a96b511f..16476310 100644
--- a/i18n/languages/messages_en.txt
+++ b/i18n/languages/messages_en.txt
@@ -177,7 +177,7 @@ import=import not permitted inside a block or loop
 import.not.found=attempt to use imported package not in package cache
 initializer.count=incorrect number of initialization values
 instruction=invalid instruction
-integer.option=invalid integer option value
+integer.value=invalid integer value
 interface.imp=missing interface implementation
 invalid.alignment.spec=invalid alignment specification
 invalid.auto=invalid use of auto increment/decrement operation
diff --git a/server/admin/logging.go b/server/admin/logging.go
index 05d29673..90535aff 100644
--- a/server/admin/logging.go
+++ b/server/admin/logging.go
@@ -76,12 +76,17 @@ func GetLoggingHandler(session *server.Session, w http.ResponseWriter, r *http.R
 // The request can optionally have a "keep" URL parameter which overrides the default number
 // of log entries to keep. A keep value of less than 1 is the same as 1.
 func PurgeLogHandler(session *server.Session, w http.ResponseWriter, r *http.Request) int {
+	var err error
+
 	keep := ui.LogRetainCount
 	q := r.URL.Query()
 
 	if v, found := q["keep"]; found {
 		if len(v) == 1 {
-			keep, _ = strconv.Atoi(v[0])
+			keep, err = strconv.Atoi(v[0])
+			if err != nil {
+				return util.ErrorResponse(w, session.ID, "Invalid keep value: "+v[0], http.StatusBadRequest)
+			}
 		}
 	}
 
diff --git a/server/assets/handler.go b/server/assets/handler.go
index ada7e287..19065280 100644
--- a/server/assets/handler.go
+++ b/server/assets/handler.go
@@ -16,6 +16,7 @@ import (
 	"github.com/tucats/ego/app-cli/ui"
 	"github.com/tucats/ego/defs"
 	"github.com/tucats/ego/server/server"
+	"github.com/tucats/ego/util"
 )
 
 // AssetsHandler is the handler for the GET method on the assets endpoint. The handler
@@ -78,11 +79,18 @@ func AssetsHandler(session *server.Session, w http.ResponseWriter, r *http.Reque
 		ranges := strings.Split(text, "-")
 
 		if len(ranges) > 0 {
-			start, _ = strconv.Atoi(ranges[0])
+			start, err = strconv.Atoi(ranges[0])
+			if err != nil {
+				return util.ErrorResponse(w, session.ID, "Invalid range header: "+h[0], http.StatusBadRequest)
+			}
 		}
 
 		if len(ranges) > 1 {
-			end, _ = strconv.Atoi(ranges[1])
+			end, err = strconv.Atoi(ranges[1])
+			if err != nil {
+				return util.ErrorResponse(w, session.ID, "Invalid range header: "+h[0], http.StatusBadRequest)
+			}
+
 			hasRange = fmt.Sprintf(" range %d-%d;", start, end)
 		}
 	}
diff --git a/server/server/admin.go b/server/server/admin.go
index 778bfff0..ef492383 100644
--- a/server/server/admin.go
+++ b/server/server/admin.go
@@ -152,7 +152,7 @@ func LogHandler(session *Session, w http.ResponseWriter, r *http.Request) int {
 
 	ui.Log(ui.RouteLogger, "[%d] Using native handler to access log lines", session.ID)
 
-	// IF present, get the "tail" value that says how many lines of output we are
+	// If present, get the "tail" value that says how many lines of output we are
 	// asked to retrieve. If not present, default to 50 lines. If th estring value
 	// is invalid, return an error response to the caller.
 	if v, found := session.Parameters["tail"]; found && len(v) > 0 {
@@ -160,7 +160,7 @@ func LogHandler(session *Session, w http.ResponseWriter, r *http.Request) int {
 		if err != nil {
 			ui.Log(ui.AuthLogger, "[%d] Unexpected error %v", session.ID, err)
 
-			return util.ErrorResponse(w, session.ID, err.Error(), http.StatusBadRequest)
+			return util.ErrorResponse(w, session.ID, "Invalid tail integer value: "+v[0], http.StatusBadRequest)
 		}
 	}
 
@@ -171,7 +171,7 @@ func LogHandler(session *Session, w http.ResponseWriter, r *http.Request) int {
 		if err != nil {
 			ui.Log(ui.AuthLogger, "[%d] Unexpected error %v", session.ID, err)
 
-			return util.ErrorResponse(w, session.ID, err.Error(), http.StatusBadRequest)
+			return util.ErrorResponse(w, session.ID, "Invalid session id value: "+v[0], http.StatusBadRequest)
 		}
 	}
 
diff --git a/server/services/cache.go b/server/services/cache.go
index 83bd6812..5d3ae27b 100644
--- a/server/services/cache.go
+++ b/server/services/cache.go
@@ -40,7 +40,13 @@ func setupServiceCache() {
 
 	if MaxCachedEntries < 0 {
 		txt := settings.Get(defs.MaxCacheSizeSetting)
-		MaxCachedEntries, _ = strconv.Atoi(txt)
+
+		n, err := strconv.Atoi(txt)
+		if err != nil {
+			ui.Log(ui.ServicesLogger, "Ignoring invalid config value for %s: %s", defs.MaxCacheSizeSetting, txt)
+		} else {
+			MaxCachedEntries = n
+		}
 	}
 
 	serviceCacheMutex.Unlock()
diff --git a/util/time.go b/util/time.go
index 9343fafd..aae6ce09 100644
--- a/util/time.go
+++ b/util/time.go
@@ -58,7 +58,7 @@ func parseDuruationWithDays(durationString string) (days int, hours int, mins in
 		if chars != "" {
 			value, err = strconv.Atoi(chars)
 			if err != nil {
-				return days, hours, mins, secs, ms, errors.New(err).Context(chars)
+				return days, hours, mins, secs, ms, errors.ErrInvalidInteger.Context(chars)
 			}
 		}
 
@@ -110,7 +110,7 @@ func parseDuruationWithDays(durationString string) (days int, hours int, mins in
 		if chars != "" {
 			mins, err = strconv.Atoi(chars)
 			if err != nil {
-				return days, hours, mins, secs, ms, errors.New(err).Context(chars)
+				return days, hours, mins, secs, ms, errors.ErrInvalidInteger.Context(chars)
 			}
 		}