diff --git a/cmd/restic/global.go b/cmd/restic/global.go
index f08a75b13..1c13fb887 100644
--- a/cmd/restic/global.go
+++ b/cmd/restic/global.go
@@ -550,9 +550,7 @@ func OpenRepository(ctx context.Context, opts GlobalOptions) (*repository.Reposi
 func parseConfig(loc location.Location, opts options.Options) (interface{}, error) {
 	cfg := loc.Config
 	if cfg, ok := cfg.(restic.ApplyEnvironmenter); ok {
-		if err := cfg.ApplyEnvironment(""); err != nil {
-			return nil, err
-		}
+		cfg.ApplyEnvironment("")
 	}
 
 	// only apply options for a particular backend here
diff --git a/internal/backend/azure/azure_test.go b/internal/backend/azure/azure_test.go
index 0fab5da26..5aee96fbd 100644
--- a/internal/backend/azure/azure_test.go
+++ b/internal/backend/azure/azure_test.go
@@ -35,11 +35,7 @@ func newAzureTestSuite(t testing.TB) *test.Suite[azure.Config] {
 				return nil, err
 			}
 
-			err = cfg.ApplyEnvironment("RESTIC_TEST_")
-			if err != nil {
-				return nil, err
-			}
-
+			cfg.ApplyEnvironment("RESTIC_TEST_")
 			cfg.Prefix = fmt.Sprintf("test-%d", time.Now().UnixNano())
 			return cfg, nil
 		},
diff --git a/internal/backend/azure/config.go b/internal/backend/azure/config.go
index 4d4e839ff..6786ec626 100644
--- a/internal/backend/azure/config.go
+++ b/internal/backend/azure/config.go
@@ -59,7 +59,7 @@ func ParseConfig(s string) (*Config, error) {
 var _ restic.ApplyEnvironmenter = &Config{}
 
 // ApplyEnvironment saves values from the environment to the config.
-func (cfg *Config) ApplyEnvironment(prefix string) error {
+func (cfg *Config) ApplyEnvironment(prefix string) {
 	if cfg.AccountName == "" {
 		cfg.AccountName = os.Getenv(prefix + "AZURE_ACCOUNT_NAME")
 	}
@@ -71,5 +71,4 @@ func (cfg *Config) ApplyEnvironment(prefix string) error {
 	if cfg.AccountSAS.String() == "" {
 		cfg.AccountSAS = options.NewSecretString(os.Getenv(prefix + "AZURE_ACCOUNT_SAS"))
 	}
-	return nil
 }
diff --git a/internal/backend/b2/b2.go b/internal/backend/b2/b2.go
index eb2cfe3c2..3560cca49 100644
--- a/internal/backend/b2/b2.go
+++ b/internal/backend/b2/b2.go
@@ -58,6 +58,13 @@ func (s *sniffingRoundTripper) RoundTrip(req *http.Request) (*http.Response, err
 }
 
 func newClient(ctx context.Context, cfg Config, rt http.RoundTripper) (*b2.Client, error) {
+	if cfg.AccountID == "" {
+		return nil, errors.Fatalf("unable to open B2 backend: Account ID ($B2_ACCOUNT_ID) is empty")
+	}
+	if cfg.Key.String() == "" {
+		return nil, errors.Fatalf("unable to open B2 backend: Key ($B2_ACCOUNT_KEY) is empty")
+	}
+
 	sniffer := &sniffingRoundTripper{RoundTripper: rt}
 	opts := []b2.ClientOption{b2.Transport(sniffer)}
 
diff --git a/internal/backend/b2/b2_test.go b/internal/backend/b2/b2_test.go
index 8e982adda..3a649db1e 100644
--- a/internal/backend/b2/b2_test.go
+++ b/internal/backend/b2/b2_test.go
@@ -35,11 +35,7 @@ func newB2TestSuite(t testing.TB) *test.Suite[b2.Config] {
 				return nil, err
 			}
 
-			err = cfg.ApplyEnvironment("RESTIC_TEST_")
-			if err != nil {
-				return nil, err
-			}
-
+			cfg.ApplyEnvironment("RESTIC_TEST_")
 			cfg.Prefix = fmt.Sprintf("test-%d", time.Now().UnixNano())
 			return cfg, nil
 		},
diff --git a/internal/backend/b2/config.go b/internal/backend/b2/config.go
index 548fbef99..94614e44f 100644
--- a/internal/backend/b2/config.go
+++ b/internal/backend/b2/config.go
@@ -85,21 +85,11 @@ func ParseConfig(s string) (*Config, error) {
 var _ restic.ApplyEnvironmenter = &Config{}
 
 // ApplyEnvironment saves values from the environment to the config.
-func (cfg *Config) ApplyEnvironment(prefix string) error {
+func (cfg *Config) ApplyEnvironment(prefix string) {
 	if cfg.AccountID == "" {
 		cfg.AccountID = os.Getenv(prefix + "B2_ACCOUNT_ID")
 	}
-
-	if cfg.AccountID == "" {
-		return errors.Fatalf("unable to open B2 backend: Account ID ($B2_ACCOUNT_ID) is empty")
-	}
-
 	if cfg.Key.String() == "" {
 		cfg.Key = options.NewSecretString(os.Getenv(prefix + "B2_ACCOUNT_KEY"))
 	}
-
-	if cfg.Key.String() == "" {
-		return errors.Fatalf("unable to open B2 backend: Key ($B2_ACCOUNT_KEY) is empty")
-	}
-	return nil
 }
diff --git a/internal/backend/gs/config.go b/internal/backend/gs/config.go
index b2d52c5f8..61a31113f 100644
--- a/internal/backend/gs/config.go
+++ b/internal/backend/gs/config.go
@@ -62,9 +62,8 @@ func ParseConfig(s string) (*Config, error) {
 var _ restic.ApplyEnvironmenter = &Config{}
 
 // ApplyEnvironment saves values from the environment to the config.
-func (cfg *Config) ApplyEnvironment(prefix string) error {
+func (cfg *Config) ApplyEnvironment(prefix string) {
 	if cfg.ProjectID == "" {
 		cfg.ProjectID = os.Getenv(prefix + "GOOGLE_PROJECT_ID")
 	}
-	return nil
 }
diff --git a/internal/backend/s3/config.go b/internal/backend/s3/config.go
index 525373d16..8dcad9eee 100644
--- a/internal/backend/s3/config.go
+++ b/internal/backend/s3/config.go
@@ -97,24 +97,14 @@ func createConfig(endpoint, bucket, prefix string, useHTTP bool) (*Config, error
 var _ restic.ApplyEnvironmenter = &Config{}
 
 // ApplyEnvironment saves values from the environment to the config.
-func (cfg *Config) ApplyEnvironment(prefix string) error {
+func (cfg *Config) ApplyEnvironment(prefix string) {
 	if cfg.KeyID == "" {
 		cfg.KeyID = os.Getenv(prefix + "AWS_ACCESS_KEY_ID")
 	}
-
 	if cfg.Secret.String() == "" {
 		cfg.Secret = options.NewSecretString(os.Getenv(prefix + "AWS_SECRET_ACCESS_KEY"))
 	}
-
-	if cfg.KeyID == "" && cfg.Secret.String() != "" {
-		return errors.Fatalf("unable to open S3 backend: Key ID ($AWS_ACCESS_KEY_ID) is empty")
-	} else if cfg.KeyID != "" && cfg.Secret.String() == "" {
-		return errors.Fatalf("unable to open S3 backend: Secret ($AWS_SECRET_ACCESS_KEY) is empty")
-	}
-
 	if cfg.Region == "" {
 		cfg.Region = os.Getenv(prefix + "AWS_DEFAULT_REGION")
 	}
-
-	return nil
 }
diff --git a/internal/backend/s3/s3.go b/internal/backend/s3/s3.go
index dd5cc36e6..10512e809 100644
--- a/internal/backend/s3/s3.go
+++ b/internal/backend/s3/s3.go
@@ -41,6 +41,12 @@ const defaultLayout = "default"
 func open(ctx context.Context, cfg Config, rt http.RoundTripper) (*Backend, error) {
 	debug.Log("open, config %#v", cfg)
 
+	if cfg.KeyID == "" && cfg.Secret.String() != "" {
+		return nil, errors.Fatalf("unable to open S3 backend: Key ID ($AWS_ACCESS_KEY_ID) is empty")
+	} else if cfg.KeyID != "" && cfg.Secret.String() == "" {
+		return nil, errors.Fatalf("unable to open S3 backend: Secret ($AWS_SECRET_ACCESS_KEY) is empty")
+	}
+
 	if cfg.MaxRetries > 0 {
 		minio.MaxRetry = int(cfg.MaxRetries)
 	}
diff --git a/internal/backend/swift/config.go b/internal/backend/swift/config.go
index b9f5d3995..5be2d9ce0 100644
--- a/internal/backend/swift/config.go
+++ b/internal/backend/swift/config.go
@@ -77,7 +77,7 @@ func ParseConfig(s string) (*Config, error) {
 var _ restic.ApplyEnvironmenter = &Config{}
 
 // ApplyEnvironment saves values from the environment to the config.
-func (cfg *Config) ApplyEnvironment(prefix string) error {
+func (cfg *Config) ApplyEnvironment(prefix string) {
 	for _, val := range []struct {
 		s   *string
 		env string
@@ -130,5 +130,4 @@ func (cfg *Config) ApplyEnvironment(prefix string) error {
 			*val.s = options.NewSecretString(os.Getenv(val.env))
 		}
 	}
-	return nil
 }
diff --git a/internal/backend/swift/swift_test.go b/internal/backend/swift/swift_test.go
index cb0992010..52278943e 100644
--- a/internal/backend/swift/swift_test.go
+++ b/internal/backend/swift/swift_test.go
@@ -48,9 +48,7 @@ func newSwiftTestSuite(t testing.TB) *test.Suite[swift.Config] {
 				return nil, err
 			}
 
-			if err = cfg.ApplyEnvironment("RESTIC_TEST_"); err != nil {
-				return nil, err
-			}
+			cfg.ApplyEnvironment("RESTIC_TEST_")
 			cfg.Prefix += fmt.Sprintf("/test-%d", time.Now().UnixNano())
 			t.Logf("using prefix %v", cfg.Prefix)
 			return cfg, nil
diff --git a/internal/restic/backend.go b/internal/restic/backend.go
index b6653fcb4..555b9d96e 100644
--- a/internal/restic/backend.go
+++ b/internal/restic/backend.go
@@ -83,5 +83,5 @@ type FileInfo struct {
 
 // ApplyEnvironmenter fills in a backend configuration from the environment
 type ApplyEnvironmenter interface {
-	ApplyEnvironment(prefix string) error
+	ApplyEnvironment(prefix string)
 }