irule to rewrite steam in request

I don't think the regsub command is corrupting the data due to a bug--I assume it's converting the content to a different encoding which is breaking the application. For the customer I was working with, using hex encoding of the find/replace strings worked well. Can you give this a try?

 
 when RULE_INIT { 
  
     Log debug messages to /var/log/ltm?  (0=none, 1=minimal, 2=verbose) 
     Verbose logging can use a lot of CPU/disk space, so use sparingly in production. 
    set ::rewrite_http_debug 2 
  
     Max collection size (in bytes) 
     As the line to rewrite is in the first few hundred bytes, this can be set to lower than the normal 1Mib. 
    set ::max_collect_size 100000 
  
     Find value (hex encoded with \x00 format) 
     https:// -> \x68\x74\x74\x70\x3a\x2f\x2f 
    set ::replace "\x68\x74\x74\x70\x3a\x2f\x2f" 
  
     Replace value (hex encoded with \x00 format) 
     http:// -> \x68\x74\x74\x70\x3a\x2f\x2f 
    set ::find "\x68\x74\x74\x70\x3a\x2f\x2f" 
  
 } 
 when HTTP_REQUEST { 
  
    if {$::rewrite_http_debug}{log local0. "[IP::client_addr]:[TCP::client_port]: New [HTTP::method] request to [HTTP::host][HTTP::uri]"} 
  
     Check for POST request with Content-Type of multipart/* 
    if {[HTTP::method] eq "POST" and [HTTP::header Content-Type] starts_with "multipart"}{ 
  
        Trigger collection of data 
       if {([HTTP::header exists "Content-Length"]) && ([HTTP::header "Content-Length"] <= $::max_collect_size)}{ 
          set content_length [HTTP::header "Content-Length"] 
       } else { 
          set content_length $::max_collect_size 
       } 
       if { [info exists content_length] } { 
          HTTP::collect $content_length 
          if {$::rewrite_http_debug}{log local0. "[IP::client_addr]:[TCP::client_port]: Collecting $content_length bytes"} 
       } 
    } 
 } 
 when HTTP_REQUEST_DATA { 
  
     Check if POST data contains the parameter name, "webLoc" 
    if {[string first "webLoc" [HTTP::payload]] ne -1}{ 
  
       if {$::rewrite_http_debug > 1}{ 
          log local0. "[IP::client_addr]:[TCP::client_port]: Found parameter name in payload" 
       } 
        Replace https:// with http:// (with search/replace strings hex-encoded to avoid encoding conversion) 
       HTTP::payload replace 0 [HTTP::payload length] [regsub -all $::find [HTTP::payload] $::replace] 
    } 
 } 
 

Aaron