How can I fix WP Super Cache error text in WordPress?

I am using wp super cache in WordPress. After months of using it, i tried deactivating. But after activating it again, i am prompted with the characters below below:

See wp-cache.php for author details. */ $wp_cache_mobile_browsers = '2.0 MMP, 240x320, 400X240, AvantGo, BlackBerry, Blazer, Cellphone, Danger, DoCoMo, Elaine/3.0, EudoraWeb, Googlebot-Mobile, hiptop, IEMobile, KYOCERA/WX310K, LG/U990, MIDP-2., MMEF20, MOT-V, NetFront, Newt, Nintendo Wii, Nitro, Nokia, Opera Mini, Palm, PlayStation Portable, portalmmm, Proxinet, ProxiNet, SHARP-TQ-GX10, SHG-i900, Small, SonyEricsson, Symbian OS, SymbianOS, TS21i-10, UP.Browser, UP.Link, webOS, Windows CE, WinWAP, YahooSeeker/M1A1-R2D2, iPhone, iPod, Android, BlackBerry9530, LG-TU915 Obigo, LGE VX, webOS, Nokia5800'; //Added by WP-Cache Manager $wp_cache_pages[ "search" ] = 0; //Added by WP-Cache Manager $wp_cache_pages[ "feed" ] = 0; //Added by WP-Cache Manager $wp_cache_pages[ "category" ] = 0; //Added by WP-Cache Manager $dismiss_readable_warning = 1; //Added by WP-Cache Manager $wp_cache_mobile_groups = ''; //Added by WP-Cache Manager $wp_cache_mobile_prefixes = 'w3c , w3c-, acs-, alav, alca, amoi, audi, avan, benq, bird, blac, blaz, brew, cell, cldc, cmd-, dang, doco, eric, hipt, htc_, inno, ipaq, ipod, jigs, kddi, keji, leno, lg-c, lg-d, lg-g, lge-, lg/u, maui, maxo, midp, mits, mmef, mobi, mot-, moto, mwbp, nec-, newt, noki, palm, pana, pant, phil, play, port, prox, qwap, sage, sams, sany, sch-, sec-, send, seri, sgh-, shar, sie-, siem, smal, smar, sony, sph-, symb, t-mo, teli, tim-, tosh, tsm-, upg1, upsi, vk-v, voda, wap-, wapa, wapi, wapp, wapr, webc, winw, winw, xda , xda-'; //Added by WP-Cache Manager $wp_cache_refresh_single_only = '0'; //Added by WP-Cache Manager $wp_cache_make_known_anon = 0; //Added by WP-Cache Manager $wp_cache_mod_rewrite = 0; //Added by WP-Cache Manager $wp_cache_front_page_checks = 0; //Added by WP-Cache Manager $wp_cache_mfunc_enabled = 0; //Added by WP-Cache Manager $wp_supercache_304 = 0; //Added by WP-Cache Manager $wp_cache_no_cache_for_get = 0; //Added by WP-Cache Manager $wp_cache_disable_utf8 = 0; //Added by WP-Cache Manager $cache_time_interval = '600'; //Added by WP-Cac

The plugin generated 6023 characters of unexpected output during activation.
If you notice “headers already sent” messages, problems with syndication
feeds or other issues, try deactivating or removing this plugin.

I am currently using WP Super Cache Version 1.4.8

Do you know how can I fix this or do I just need to update to a recent version?