Export of relation fields throws SQL error

When trying to export contacts after doing an advanced search, I get the following error message:

Sorry. A non-recoverable error has occurred.
DB Error: value count on row
Error Details
Database Error Code: Column count doesn't match value count at row 1, 1136
Additional Details:
Array
(
[callback] => Array
(
[0] => CRM_Core_Error
[1] => handle
)

[code] => -22
[message] => DB Error: value count on row
[mode] => 16
[debug_info] =>
INSERT INTO civicrm_export_temp (id, first_name,last_name)
VALUES (1,'','','')
[nativecode=1136 ** Column count doesn't match value count at row 1]
[type] => DB_Error
[user_info] =>
INSERT INTO civicrm_export_temp (id, first_name,last_name)
VALUES (1,'','','')
[nativecode=1136 ** Column count doesn't match value count at row 1]
[to_string] => [db_error: message="DB Error: value count on row" code=-22 mode=callback callback=CRM_Core_Error::handle prefix="" info="
INSERT INTO civicrm_export_temp (id, first_name,last_name)
VALUES (1,'','','')
[nativecode=1136 ** Column count doesn't match value count at row 1]"]
)

To reproduce this issue in the civicrm sandbox:

• Click Search --> Advanced Search
• Choose as the criteria: relationship is "Volunteer of"
• In the list of batch actions, choose "Export Contacts"
• Choose "Select fields for export" then click continue
• In the list of fields to export, choose "first name" , "last name", "Volunteer for" ... "Extra Volunteer Relationship Info...Sample field 1 " ( This is a custom field)