# 7.3.6.3.1. `-2: GRN_OPERATION_NOT_PERMITTED`

## 7.3.6.3.1.1. Major cause

1. If the table that is a target of `table_remove` has reference from other table and column.

2. If the number of threads is greater than 1 when we execute `database_unmap`.

3. (Windows only) If network access is denied.

## 7.3.6.3.1.2. Major action on this error

1. If the table that is a target of `table_remove` has reference from other table and column.

   We remove tables and columns of the reference sources.

2. If the number of threads is greater than 1 when we execute `database_unmap`.

   We make the number of threads one by executing `thread_limit max=1`.

3. (Windows only) If network access is denied.

   We confirm the status network(e.g. confirm whether the server process starting, confirm the setting of the firewall, and so on).