Problem with Drupal template i bought

I bought a drupal theme from themeforest for my company, i uploaded files and sql as instructed by the author. I logged into backend to edit and add my contents, but everytime when i edited content and clicked save button, page was broken with error messages like below.

The website encountered an unexpected error. Please try again later.</br></br><em class="placeholder">DrupalCoreEntityEntityStorageException</em>: SQLSTATE[HY000]: General error: 1364 Field 'vid' doesn't have a default value: INSERT INTO {node_revision} (nid, langcode, revision_uid, revision_timestamp, revision_log) VALUES (:db_insert_placeholder_0, :db_insert_placeholder_1, :db_insert_placeholder_2, :db_insert_placeholder_3, :db_insert_placeholder_4); Array
(
    [:db_insert_placeholder_0] =&gt; 165
    [:db_insert_placeholder_1] =&gt; en
    [:db_insert_placeholder_2] =&gt; 1
    [:db_insert_placeholder_3] =&gt; 1527578309
    [:db_insert_placeholder_4] =&gt; 
)
 in <em class="placeholder">DrupalCoreEntitySqlSqlContentEntityStorage-&gt;save()</em> (line <em class="placeholder">805</em> of <em class="placeholder">core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorage.php</em>). <pre class="backtrace">DrupalCoreDatabaseStatement-&gt;execute(Array, Array) (Line: 625)
DrupalCoreDatabaseConnection-&gt;query('INSERT INTO {node_revision} (nid, langcode, revision_uid, revision_timestamp, revision_log) VALUES (:db_insert_placeholder_0, :db_insert_placeholder_1, :db_insert_placeholder_2, :db_insert_placeholder_3, :db_insert_placeholder_4)', Array, Array) (Line: 87)
DrupalCoreDatabaseDrivermysqlConnection-&gt;query('INSERT INTO {node_revision} (nid, langcode, revision_uid, revision_timestamp, revision_log) VALUES (:db_insert_placeholder_0, :db_insert_placeholder_1, :db_insert_placeholder_2, :db_insert_placeholder_3, :db_insert_placeholder_4)', Array, Array) (Line: 32)
DrupalCoreDatabaseDrivermysqlInsert-&gt;execute() (Line: 1077)
DrupalCoreEntitySqlSqlContentEntityStorage-&gt;saveRevision(Object) (Line: 854)
DrupalCoreEntitySqlSqlContentEntityStorage-&gt;doSaveFieldItems(Object) (Line: 257)
DrupalCoreEntityContentEntityStorageBase-&gt;doSave('165', Object) (Line: 392)
DrupalCoreEntityEntityStorageBase-&gt;save(Object) (Line: 796)
DrupalCoreEntitySqlSqlContentEntityStorage-&gt;save(Object) (Line: 377)
DrupalCoreEntityEntity-&gt;save() (Line: 286)
DrupalnodeNodeForm-&gt;save(Array, Object)
call_user_func_array(Array, Array) (Line: 111)
DrupalCoreFormFormSubmitter-&gt;executeSubmitHandlers(Array, Object) (Line: 51)
DrupalCoreFormFormSubmitter-&gt;doSubmitForm(Array, Object) (Line: 585)
DrupalCoreFormFormBuilder-&gt;processForm('node_page_edit_form', Array, Object) (Line: 314)
DrupalCoreFormFormBuilder-&gt;buildForm('node_page_edit_form', Object) (Line: 74)
DrupalCoreControllerFormController-&gt;getContentResult(Object, Object)
call_user_func_array(Array, Array) (Line: 123)
DrupalCoreEventSubscriberEarlyRenderingControllerWrapperSubscriber-&gt;DrupalCoreEventSubscriber{closure}() (Line: 582)
DrupalCoreRenderRenderer-&gt;executeInRenderContext(Object, Object) (Line: 124)
DrupalCoreEventSubscriberEarlyRenderingControllerWrapperSubscriber-&gt;wrapControllerExecutionInRenderContext(Array, Array) (Line: 97)
DrupalCoreEventSubscriberEarlyRenderingControllerWrapperSubscriber-&gt;DrupalCoreEventSubscriber{closure}()
call_user_func_array(Object, Array) (Line: 153)
SymfonyComponentHttpKernelHttpKernel-&gt;handleRaw(Object, 1) (Line: 68)
SymfonyComponentHttpKernelHttpKernel-&gt;handle(Object, 1, 1) (Line: 57)
DrupalCoreStackMiddlewareSession-&gt;handle(Object, 1, 1) (Line: 47)
DrupalCoreStackMiddlewareKernelPreHandle-&gt;handle(Object, 1, 1) (Line: 99)
Drupalpage_cacheStackMiddlewarePageCache-&gt;pass(Object, 1, 1) (Line: 78)
Drupalpage_cacheStackMiddlewarePageCache-&gt;handle(Object, 1, 1) (Line: 47)
DrupalCoreStackMiddlewareReverseProxyMiddleware-&gt;handle(Object, 1, 1) (Line: 50)
DrupalCoreStackMiddlewareNegotiationMiddleware-&gt;handle(Object, 1, 1) (Line: 23)
StackStackedHttpKernel-&gt;handle(Object, 1, 1) (Line: 657)
DrupalCoreDrupalKernel-&gt;handle(Object) (Line: 18)
</pre>

I tried to contact the theme author, but sadly, he did not respond even though themeforest said i had 4 more month of support.

Anyone has solution to this problem? any thoughts?

Appreciate your help.

Drupal version: 


Source: https://www.drupal.org/taxonomy/term/3/feed