Angular with Prerender (.htaccess settings) - angularjs

Question

I am trying to set up Angular 1.5 app for server side rendering for the crawlers by using Prerender service.
And everything works fine for the inner pages but there is a problem with the main page's rendering - the crawler sees the 404 page instead of the main page.
I suppose there is a problem with some other rules in my .htaccess - except the rules for the Prerender, I use two other rules for all the pages:
rewriting urls without trailing slashes onto the urls with trailing slashes
rewriting urls with www on the urls without www
Will be appreciate for any tips!
Here is my .htaccess file for Apache serveer
RequestHeader set X-Prerender-Token "MyToken"
RewriteEngine On
RewriteCond %{HTTP_HOST} ^www.example.com$ [NC]
RewriteRule ^(.*)$ http://example.com/$1 [R=301,L]
# If an existing asset or directory is requested go to it as it is
RewriteCond %{DOCUMENT_ROOT}%{REQUEST_URI} -f [OR]
RewriteCond %{DOCUMENT_ROOT}%{REQUEST_URI} -d
RewriteRule ^ - [L]
RewriteCond %{REQUEST_URI} ^/$
RewriteCond %{QUERY_STRING} ^_escaped_fragment_=/?(.*)$
RewriteRule ^(.*)$ /snapshots/%1? [NC,L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^(.*[^/])$ /$1/ [L,R=301]
<IfModule mod_proxy_http.c>
RewriteCond %{HTTP_USER_AGENT} Googlebot|bingbot|Googlebot-Mobile|Baiduspider|Yahoo|YahooSeeker|DoCoMo|Twitterbot|TweetmemeBot|Twikle|Netseer|Daumoa|SeznamBot|Ezooms|MSNBot|Exabot|MJ12bot|sogou\sspider|YandexBot|bitlybot|ia_archiver|proximic|spbot|ChangeDetection|NaverBot|MetaJobBot|magpie-crawler|Genieo\sWeb\sfilter|Qualidator.com\sBot|Woko|Vagabondo|360Spider|ExB\sLanguage\sCrawler|AddThis.com|aiHitBot|Spinn3r|BingPreview|GrapeshotCrawler|CareerBot|ZumBot|ShopWiki|bixocrawler|uMBot|sistrix|linkdexbot|AhrefsBot|archive.org_bot|SeoCheckBot|TurnitinBot|VoilaBot|SearchmetricsBot|Butterfly|Yahoo!|Plukkie|yacybot|trendictionbot|UASlinkChecker|Blekkobot|Wotbox|YioopBot|meanpathbot|TinEye|LuminateBot|FyberSpider|Infohelfer|linkdex.com|Curious\sGeorge|Fetch-Guess|ichiro|MojeekBot|SBSearch|WebThumbnail|socialbm_bot|SemrushBot|Vedma|alexa\ssite\saudit|SEOkicks-Robot|Browsershots|BLEXBot|woriobot|AMZNKAssocBot|Speedy|oBot|HostTracker|OpenWebSpider|WBSearchBot|FacebookExternalHit [NC,OR]
RewriteCond %{QUERY_STRING} _escaped_fragment_
# Only proxy the request to Prerender if it's a request for HTML
RewriteRule ^(?!.*?(\.js|\.css|\.xml|\.less|\.png|\.jpg|\.jpeg|\.gif|\.pdf|\.doc|\.txt|\.ico|\.rss|\.zip|\.mp3|\.rar|\.exe|\.wmv|\.doc|\.avi|\.ppt|\.mpg|\.mpeg|\.tif|\.wav|\.mov|\.psd|\.ai|\.xls|\.mp4|\.m4a|\.swf|\.dat|\.dmg|\.iso|\.flv|\.m4v|\.torrent|\.ttf|\.woff))(.*) http://service.prerender.io/http://example.com/$2 [P,L]
</IfModule>
# If the requested resource doesn't exist, use index.html
RewriteRule ^ /index.html

Answer 1

You have this section:
RewriteCond %{REQUEST_URI} ^/$
RewriteCond %{QUERY_STRING} ^_escaped_fragment_=/?(.*)$
RewriteRule ^(.*)$ /snapshots/%1? [NC,L]
Which will try to serve files from your /snapshots/ directory if _escaped_fragment_ is in the URL. That doesn't have anything to do with Prerender.io so you'll probably want to remove that section, as it could be the cause of the 404.
You're also checking Googlebot and Bingbot by their user agents which is a bad idea because they could penalize you for cloaking.