diff --git a/builder/xenserver/common/common_config.go b/builder/xenserver/common/common_config.go
index 4ae5edd..bf63ae2 100644
--- a/builder/xenserver/common/common_config.go
+++ b/builder/xenserver/common/common_config.go
@@ -20,7 +20,7 @@ type CommonConfig struct {
 	VMName             string   `mapstructure:"vm_name"`
 	VMDescription      string   `mapstructure:"vm_description"`
 	SrName             string   `mapstructure:"sr_name"`
-	SrISOName          string   `mapstructure:"sr_iso_name"`
+	SrISOName          string   `mapstructure:"sr_iso_name" required:"false"`
 	FloppyFiles        []string `mapstructure:"floppy_files"`
 	NetworkNames       []string `mapstructure:"network_names"`
 	ExportNetworkNames []string `mapstructure:"export_network_names"`
@@ -223,29 +223,11 @@ func (c CommonConfig) ShouldKeepVM(state multistep.StateBag) bool {
 }
 
 func (config CommonConfig) GetSR(c *Connection) (xenapi.SRRef, error) {
-	var srRef xenapi.SRRef
 	if config.SrName == "" {
-		hostRef, err := c.GetClient().Session.GetThisHost(c.session, c.session)
-
-		if err != nil {
-			return srRef, err
-		}
-
-		pools, err := c.GetClient().Pool.GetAllRecords(c.session)
-
-		if err != nil {
-			return srRef, err
-		}
-
-		for _, pool := range pools {
-			if pool.Master == hostRef {
-				return pool.DefaultSR, nil
-			}
-		}
-
-		return srRef, errors.New(fmt.Sprintf("failed to find default SR on host '%s'", hostRef))
-
+		return getDefaultSR(c)
 	} else {
+		var srRef xenapi.SRRef
+
 		// Use the provided name label to find the SR to use
 		srs, err := c.GetClient().SR.GetByNameLabel(c.session, config.SrName)
 
@@ -267,7 +249,7 @@ func (config CommonConfig) GetSR(c *Connection) (xenapi.SRRef, error) {
 func (config CommonConfig) GetISOSR(c *Connection) (xenapi.SRRef, error) {
 	var srRef xenapi.SRRef
 	if config.SrISOName == "" {
-		return srRef, errors.New("sr_iso_name must be specified in the packer configuration")
+		return getDefaultSR(c)
 
 	} else {
 		// Use the provided name label to find the SR to use
@@ -287,3 +269,34 @@ func (config CommonConfig) GetISOSR(c *Connection) (xenapi.SRRef, error) {
 		return srs[0], nil
 	}
 }
+
+func getDefaultSR(c *Connection) (xenapi.SRRef, error) {
+	var srRef xenapi.SRRef
+	client := c.GetClient()
+	hostRef, err := client.Session.GetThisHost(c.session, c.session)
+
+	if err != nil {
+		return srRef, err
+	}
+
+	// The current version of the go-xen-api-client does not fully support XenAPI version 8.2
+	// In particular, some values for the pool `allowed_operations` are not recognised, resulting
+	// in a parse error when retrieving pool records. As a workaround, we only fetch pool refs.
+	pool_refs, err := client.Pool.GetAll(c.session)
+
+	if err != nil {
+		return srRef, err
+	}
+
+	for _, pool_ref := range pool_refs {
+		pool_master, err := client.Pool.GetMaster(c.session, pool_ref)
+		if err != nil {
+			return srRef, err
+		}
+		if pool_master == hostRef {
+			return client.Pool.GetDefaultSR(c.session, pool_ref)
+		}
+	}
+
+	return srRef, errors.New(fmt.Sprintf("failed to find default SR on host '%s'", hostRef))
+}
diff --git a/builder/xenserver/common/config.hcl2spec.go b/builder/xenserver/common/config.hcl2spec.go
index 04d4479..9b3fcb7 100644
--- a/builder/xenserver/common/config.hcl2spec.go
+++ b/builder/xenserver/common/config.hcl2spec.go
@@ -24,7 +24,7 @@ type FlatConfig struct {
 	VMName                    *string           `mapstructure:"vm_name" cty:"vm_name" hcl:"vm_name"`
 	VMDescription             *string           `mapstructure:"vm_description" cty:"vm_description" hcl:"vm_description"`
 	SrName                    *string           `mapstructure:"sr_name" cty:"sr_name" hcl:"sr_name"`
-	SrISOName                 *string           `mapstructure:"sr_iso_name" cty:"sr_iso_name" hcl:"sr_iso_name"`
+	SrISOName                 *string           `mapstructure:"sr_iso_name" required:"false" cty:"sr_iso_name" hcl:"sr_iso_name"`
 	FloppyFiles               []string          `mapstructure:"floppy_files" cty:"floppy_files" hcl:"floppy_files"`
 	NetworkNames              []string          `mapstructure:"network_names" cty:"network_names" hcl:"network_names"`
 	ExportNetworkNames        []string          `mapstructure:"export_network_names" cty:"export_network_names" hcl:"export_network_names"`