What is wrong in my php settings?

My laravel application in some cases need to upload Excel files, if the excel file is less than 1.5MB, everything works correctly, but if the excel file more than 1.5MB it shows HTTP error

This page isn’t working

127.0.0.1 is currently unable to handle this request.

HTTP ERROR 500

My php.ini settings is like this ( I removed almost all comments)

[PHP]
engine = On
short_open_tag = Off
precision = 14
output_buffering = 20480
zlib.output_compression = Off
implicit_flush = Off
unserialize_callback_func =
serialize_precision = 17
disable_functions =
disable_classes =
zend.enable_gc = On

expose_php = On
max_execution_time = 300
max_input_time = 300
max_input_vars = 2500
memory_limit = 512M
error_reporting = E_ALL
display_errors = On
display_startup_errors = On
log_errors = On
log_errors_max_len = 1024
ignore_repeated_errors = Off
ignore_repeated_source = Off
report_memleaks = On
track_errors = On
html_errors = On
error_log ="c:/wamp64/logs/php_error.log"
variables_order = "GPCS"
request_order = "GP"
register_argc_argv = Off
auto_globals_jit = Off
post_max_size = 50M
default_mimetype = "text/html"
extension_dir ="c:/wamp64/bin/php/php7.0.10/ext/"
enable_dl = Off
file_uploads = On
upload_tmp_dir ="c:/wamp64/tmp"
upload_max_filesize = 50M
max_file_uploads = 5
allow_url_fopen = On
allow_url_include = Off
default_socket_timeout = 300

extension=php_bz2.dll
extension=php_curl.dll
extension=php_com_dotnet.dll
;extension=php_enchant.dll
extension=php_fileinfo.dll
;extension=php_ftp.dll
extension=php_gd2.dll
extension=php_gettext.dll
extension=php_gmp.dll
extension=php_intl.dll
extension=php_imap.dll
;extension=php_interbase.dll
extension=php_ldap.dll
extension=php_mbstring.dll
extension=php_exif.dll      ; Must be after mbstring as it depends on it
extension=php_mysqli.dll
;extension=php_oci8_12c.dll
;extension=php_odbc.dll
extension=php_openssl.dll
;extension=php_pdo_firebird.dll
extension=php_pdo_mysql.dll
;extension=php_pdo_oci.dll
;extension=php_pdo_odbc.dll
;extension=php_pdo_pgsql.dll
extension=php_pdo_sqlite.dll
;extension=php_pgsql.dll
;extension=php_phpdbg_webhelper.dll
;extension=php_shmop.dll
;extension=php_snmp.dll
extension=php_soap.dll
extension=php_sockets.dll
extension=php_sqlite3.dll
;extension=php_sysvshm.dll
;extension=php_tidy.dll
extension=php_xmlrpc.dll
extension=php_xsl.dll

[Session]
session.save_handler = files
session.save_path ="c:/wamp64/tmp"
session.use_strict_mode = 0
session.use_cookies = 1
session.use_only_cookies = 1
session.name = PHPSESSID
session.auto_start = 0
session.cookie_lifetime = 0
session.cookie_path = /
session.cookie_domain =
session.cookie_httponly =
session.serialize_handler = php
session.gc_probability = 1
session.gc_divisor = 1000
session.gc_maxlifetime = 1440
session.referer_check =
session.cache_limiter = nocache
session.cache_expire = 180
session.use_trans_sid = 0
session.hash_function = 0
session.hash_bits_per_character = 5
url_rewriter.tags = "a=href,area=href,frame=src,input=src,form=fakeentry"