Since I switched to latest SBCL sometimes I got following error:
Internal Server Error
The value NIL is not of type STRING.
0: (BACKTRACE 536870911 #<SB-IMPL::STRING-OUTPUT-STREAM {CD0F3C9}>) 1: (HUNCHENTOOT:GET-BACKTRACE #<unavailable argument>) 2: ((LAMBDA (COND)) #<TYPE-ERROR {CD0F2A9}>) 3: ((LAMBDA (COND)) #<TYPE-ERROR {CD0F2A9}>) 4: (SIGNAL #<TYPE-ERROR {CD0F2A9}>) 5: (ERROR TYPE-ERROR) 6: (SB-KERNEL::OBJECT-NOT-TYPE-ERROR-HANDLER #<unavailable argument> #.(SB-SYS:INT-SAP #XB505254C) #<SB-ALIEN-INTERNALS:ALIEN-VALUE :SAP #XB505223C :TYPE (* (STRUCT
SB-VM::OS-CONTEXT-T-STRUCT))> (142 14)) 7: (SB-KERNEL::OBJECT-NOT-TYPE-ERROR-HANDLER #<unavailable argument> #.(SB-SYS:INT-SAP #XB505254C) #<SB-ALIEN-INTERNALS:ALIEN-VALUE :SAP #XB505223C :TYPE (* (STRUCT
SB-VM::OS-CONTEXT-T-STRUCT))> (142 14)) 8: (SB-KERNEL:INTERNAL-ERROR #.(SB-SYS:INT-SAP #XB505223C) #<unavailable argument>) 9: ("foreign function: call_into_lisp") 10: ("foreign function: funcall2") 11: ("foreign function: interrupt_internal_error") 12: ("foreign function: sigtrap_handler") 13: (MAKE-STRING-INPUT-STREAM NIL 0) 14: (NIL NIL) 15: (CP-API::UPLOAD-FILE "10f14f8c-016c-479a-9709-ce62b2027149" #P"/tmp/upload/6E5824411F6BBA0248441CFCDF13D765-text.png" "Customers") 16: (CP-API::SESSION-GENERATE-DESIGN) 17: (CP-API::CP-PRODUCT) 18: (HUNCHENTOOT::PROCESS-REQUEST ((:HOST . "127.0.0.1:3001") (:ACCEPT . "image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, application/x-shockwave-flash, */*") (:ACCEPT-ENCODING . "gzip, deflate") (:ACCEPT-LANGUAGE . "en-us") (:COOKIE . "sessionid=52%3A6E5824411F6BBA0248441CFCDF13D765") (:UA-CPU . "x86") (:USER-AGENT . "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR 1.0.3705; .NET CLR 1.1.4322; .NET CLR 2.0.50727; Media Center PC 4.0)") (:X-FORWARDED-FOR . "192.168.1.1") (:X-FORWARDED-HOST . "www.greenpixeldesign.com") (:X-FORWARDED-SERVER . "www.greenpixeldesign.com") (:CONNECTION . "close")) #<FLEXI-STREAMS::FLEXI-LATIN-1-IO-STREAM {CBCADE9}> :GET "/cphandler/product.html" :HTTP/1.1) 19: (HUNCHENTOOT::PROCESS-CONNECTION #<HUNCHENTOOT::SERVER {A96A0C9}> #<SB-BSD-SOCKETS:INET-SOCKET descriptor 14 {CBC2559}>) 20: ((LAMBDA ())) 21: ("foreign function: call_into_lisp") 22: ("foreign function: funcall0") 23: ("foreign function: new_thread_trampoline") 24: ("foreign function: #xB7FD5B63")