Did you get the mysqldump issue fixed?
What does /var/upgrade/core_log.txt say now?
################################################################################
################################################################################
2018-11-26 09:30:03: Starting installation of the "core" upgrade package
2018-11-26 09:30:03: Upgrading version 4.9.1 to 4.9.2
2018-11-26 09:30:03: Running as user "tzxtgxev"
2018-11-26 09:30:03: Storing entry point files permissions...
2018-11-26 09:30:03: index.php ==> 33188 (-rw-r--r--)
2018-11-26 09:30:03: abulhoul_panel.php ==> 33188 (-rw-r--r--)
2018-11-26 09:30:03: api.php ==> 33188 (-rw-r--r--)
2018-11-26 09:30:03: vendor.php ==> 33188 (-rw-r--r--)
2018-11-26 09:30:03: ==> 16872 (drwxr-x---)
2018-11-26 09:30:03: Executing pre-upgrade validators
2018-11-26 09:30:03: Found 0 validators at package
2018-11-26 09:30:03: Executing "collisions" validator
2018-11-26 09:30:03: Executing "permissions" validator
2018-11-26 09:30:03: Executing "restore" validator
2018-11-26 09:30:03: Backup filename is "upg_core_4.9.1-4.9.2_26Nov2018_093003"
2018-11-26 09:30:03: Preparing restore script
2018-11-26 09:30:03: Upgrades directory permissions: drwxr-xr-x tzxtgxev:tzxtgxev
2018-11-26 09:30:03: Source restore script permissions: -rw-r--r-- tzxtgxev:tzxtgxev
2018-11-26 09:30:03: Created directory for restore script at "/home/tzxtgxev/public_html/upgrades/core_4.9.1-4.9.2/"
2018-11-26 09:30:03: Directory permissions: drwxr-xr-x tzxtgxev:tzxtgxev
2018-11-26 09:30:04: Created restore script at "/home/tzxtgxev/public_html/upgrades/core_4.9.1-4.9.2/restore_2018-11-26_09-30-03.php"
2018-11-26 09:30:04: Restore script permissions: -rw-r--r-- tzxtgxev:tzxtgxev
2018-11-26 09:30:04: Correcting target restore script directory permissions...
2018-11-26 09:30:04: ----------
2018-11-26 09:30:04: Changing permissions of "/home/tzxtgxev/public_html/upgrades/core_4.9.1-4.9.2/" to 755
2018-11-26 09:30:04: Using chmod()... OK
2018-11-26 09:30:04: ----------
2018-11-26 09:30:04: Target restore script directory permissions: drwxr-xr-x tzxtgxev:tzxtgxev
2018-11-26 09:30:04: Correcting upgrades directory permissions...
2018-11-26 09:30:04: ----------
2018-11-26 09:30:04: Changing permissions of "/home/tzxtgxev/public_html/upgrades" to 755
2018-11-26 09:30:04: Using chmod()... OK
2018-11-26 09:30:04: ----------
2018-11-26 09:30:04: Upgrades directory permissions: drwxr-xr-x tzxtgxev:tzxtgxev
2018-11-26 09:30:04: Checking restore script availability via HTTP
2018-11-26 09:30:04: Executing pre-upgrade script "/home/tzxtgxev/public_html/var/upgrade/packages/core/content/scripts/pre_script.php"
2018-11-26 09:30:04: Pre-upgrade script executed successfully
2018-11-26 09:30:04: Closing storefront
2018-11-26 09:30:04: Backing up files and database
2018-11-26 09:30:04: mysqldump is not available
2018-11-26 09:34:35: Backup created at "/home/tzxtgxev/public_html/var/backups/upg_core_4.9.1-4.9.2_26Nov2018_093003.zip"
2018-11-26 09:34:35: Sending upgrade information e-mail to: melshity@abulhoul.com, melshity@gmail.com
2018-11-26 09:34:35: E-mail was successfully sent
2018-11-26 09:34:35: Executing 7 migrations found at package
2018-11-26 09:34:35:
2018-11-26 09:34:35: using config file ./app/Tygh/UpgradeCenter/Migrations/config.migrations.php
2018-11-26 09:34:35: using config parser php
2018-11-26 09:34:35: using migration path /home/tzxtgxev/public_html/var/upgrade/packages/core/content/migrations
2018-11-26 09:34:35: using environment development
2018-11-26 09:34:35: using adapter mysqli
2018-11-26 09:34:35: using database tzxtgxev_abulhouldb
2018-11-26 09:34:35: -- createTable('phinxlog1543217403')
2018-11-26 09:34:35: -> 0.0047s
2018-11-26 09:34:35:
2018-11-26 09:34:35: == 20181004083033 CoreDocumentsSnippetsProductTableRowsImprove: migrating
2018-11-26 09:34:35: == 20181004083033 CoreDocumentsSnippetsProductTableRowsImprove: migrated 0.0010s
2018-11-26 09:34:35:
2018-11-26 09:34:35: == 20181016091004 AddonsSmsNotificationsRemoveObsoleteSettings: migrating
2018-11-26 09:34:35: == 20181016091004 AddonsSmsNotificationsRemoveObsoleteSettings: migrated 0.0007s
2018-11-26 09:34:35:
2018-11-26 09:34:35: == 20181017102411 AddonsDiscussionAddReviewReturnAnonymousApprovalOption: migrating
2018-11-26 09:34:35: == 20181017102411 AddonsDiscussionAddReviewReturnAnonymousApprovalOption: migrated 0.0035s
2018-11-26 09:34:35:
2018-11-26 09:34:35: == 20181018123537 AddonsOnekpayRenameToBillriantPay: migrating
2018-11-26 09:34:35: == 20181018123537 AddonsOnekpayRenameToBillriantPay: migrated 0.0008s
2018-11-26 09:34:35:
2018-11-26 09:34:35: == 20181019061641 CoreRenameDeprecatedFuturePayPayments: migrating
2018-11-26 09:34:35: == 20181019061641 CoreRenameDeprecatedFuturePayPayments: migrated 0.0011s
2018-11-26 09:34:35:
2018-11-26 09:34:35: == 20181019120805 CoreDatabaseAddNewGreeceRegions: migrating
2018-11-26 09:34:35: == 20181019120805 CoreDatabaseAddNewGreeceRegions: migrated 0.0392s
2018-11-26 09:34:35:
2018-11-26 09:34:35: == 20181030113131 AddonsOnekpayChangeLangvars: migrating
2018-11-26 09:34:35: == 20181030113131 AddonsOnekpayChangeLangvars: migrated 0.0014s
2018-11-26 09:34:35:
2018-11-26 09:34:35: All Done. Took 0.0741s
2018-11-26 09:34:35: Migrations were executed successfully
2018-11-26 09:34:35: Copying package files
2018-11-26 09:35:00: Deleting files removed at new version
2018-11-26 09:35:00: Processing themes files
2018-11-26 09:35:01: Installing languages using upgraded *.po files
2018-11-26 09:35:01: Already installed languages: en, ar
2018-11-26 09:35:01: Languages to be installed: ar, cs, da, de, el, en, es, fr, hu, id, it, ja, nl, no, pl, ro, ru, sk, sr, sv, tr, uk, vi, zh
2018-11-26 09:35:01: Installing "en" language...