I have fixed this issue. And I have 2 solutions for that.
The first one: Clean up your database in table url_rewrite (Change the url_key of all category). You can write UpgradeData script for this solution.
The second one: Remove the duplication data when saving category.
This data is throw in method doReplace($urls) in \vendor\magento\module-url-rewrite\Model\Storage\DbStorage.php file.
protected function doReplace($urls)
{
foreach ($this->createFilterDataBasedOnUrls($urls) as $type => $urlData) {
$urlData[UrlRewrite::ENTITY_TYPE] = $type;
$this->deleteByData($urlData);
}
$data = [];
foreach ($urls as $url) {
$data[] = $url->toArray();
}
$this->insertMultiple($data);
}
After debugging, I found out $data variable have duplicate record. If you want this method to work without any errors, rewrite this method above to:
protected function doReplace($urls)
{
foreach ($this->createFilterDataBasedOnUrls($urls) as $type => $urlData) {
$urlData[UrlRewrite::ENTITY_TYPE] = $type;
$this->deleteByData($urlData);
}
$data = [];
$storeId_requestPaths = [];
foreach ($urls as $url) {
$storeId = $url->getStoreId();
$requestPath = $url->getRequestPath();
// Skip if is exist in the database
$sql = "SELECT * FROM url_rewrite where store_id = $storeId and request_path = '$requestPath'";
$exists = $this->connection->fetchOne($sql);
if ($exists) continue;
$storeId_requestPaths[] = $storeId . '-' . $requestPath;
$data[] = $url->toArray();
}
// Remove duplication data;
$n = count($storeId_requestPaths);
for ($i = 0; $i < $n - 1; $i++) {
for ($j = $i + 1; $j < $n; $j++) {
if ($storeId_requestPaths[$i] == $storeId_requestPaths[$j]) {
unset($data[$j]);
}
}
}
$this->insertMultiple($data);
}
If you want to get more details, please read my comment in:
https://github.com/magento/magento2/issues/7298
Hope this will help you.
URL Keykey of category where you get this error. this will fix your issue