Unable to allocate memory for pool problem

Whenever I go to my login dashboard on wordpress, the following message appears. When I finally get in to Wordpress admin after a few clicks to different sections - the same message keeps displaying at the top (then I scroll down and the admin panel shows.

What is causing this? The php memory is set to 256 and i've tried upping it to 512 and still the same issue persists. Can anyone suggest a fix:

Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 425 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 426 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 427 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 430 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 431 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 432 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 433 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 434 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 435 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 436 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 437 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 438 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 439 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 440 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 441 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 442 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 443 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 444 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 445 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 446 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 447 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 448 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 449 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 450 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 451 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 452 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 453 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 454 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 455 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 461 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 464 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 466 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 467 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 468 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 469 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 471 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 472 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 473 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 474 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 475 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 476 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 477 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 478 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 479 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 480 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/includes/admin/notices.php on line 82 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/includes/admin/notices.php on line 85 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 483 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 484 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 485 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 486 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 487 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 488 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 489 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 490 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 491 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 492 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 493 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 494 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 495 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 496 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 497 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 498 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 499 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 506 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 509 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 510 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 513 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 514 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 515 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 516 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 517 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 518 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 519 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 520 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 521 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 522 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 525 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 533 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 536 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 539 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 547 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 550 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 553 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 556 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 567 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 570 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 573 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 574 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 575 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 576 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 577 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 578 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 579 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 580 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 581 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 582 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 583 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 584 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 585 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 586 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 587 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 588 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 589 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 590 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 591 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php on line 593 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/classes/session.php on line 50 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/classes/session.php on line 53 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/classes/session.php on line 54 Warning: include_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-settings.php on line 304 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/revslider/revslider.php on line 59 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/revslider/includes/framework/include-framework.php on line 12 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/revslider/includes/framework/include-framework.php on line 13 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/revslider/includes/framework/include-framework.php on line 14 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/revslider/includes/framework/include-framework.php on line 15 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/revslider/includes/framework/include-framework.php on line 16 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/revslider/includes/framework/include-framework.php on line 17 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/revslider/includes/framework/include-framework.php on line 18 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/revslider/includes/framework/include-framework.php on line 19 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/revslider/includes/framework/include-framework.php on line 20 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/revslider/includes/framework/include-framework.php on line 21 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/revslider/revslider.php on line 62 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/revslider/revslider.php on line 63 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/revslider/revslider.php on line 64 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/revslider/revslider.php on line 65 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/revslider/revslider.php on line 68 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/revslider/revslider.php on line 69 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/revslider/revslider.php on line 70 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/revslider/revslider.php on line 71 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/revslider/revslider.php on line 72 Warning: require_once(): Unable to allocate memory for pool. in /var/www/vhosts/httpdocs/wp-content/plugins/revslider/revslider.php on line 73 Warning: Cannot modify header information - headers already sent by (output started at /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php:450) in /var/www/vhosts/httpdocs/wp-login.php on line 394 Warning: Cannot modify header information - headers already sent by (output started at /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php:450) in /var/www/vhosts/httpdocs/wp-login.php on line 407 Warning: Cannot modify header information - headers already sent by (output started at /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php:450) in /var/www/vhosts/httpdocs/wp-includes/pluggable.php on line 893 Warning: Cannot modify header information - headers already sent by (output started at /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php:450) in /var/www/vhosts/httpdocs/wp-includes/pluggable.php on line 894 Warning: Cannot modify header information - headers already sent by (output started at /var/www/vhosts/httpdocs/wp-content/plugins/ninja-forms/deprecated/ninja-forms.php:450) in /var/www/vhosts/httpdocs/wp-includes/pluggable.php on line 895