Why does ssh2_exec(): Unable to request command execution occur?

Question

PHP

Hello, does anyone know what could be the problem.
In php, I connect to a remote server via ssh2 and try to send a command to write text to a file to it.

cat <<EOF > /test
$TEXT
EOF

The number of characters in the $TEXT variable is approximately 38000. An error occurs:
Warning: ssh2_exec (): Unable to request command execution on remote host in ...
With a smaller number of characters, the error disappears and it records everything well. The approximate number of characters at which the recording passes is 34000, if in Cyrillic, then 20000
====
Filled the text with zeros, the exact value that it successfully passes through the echo $data > $file command is 34691, the final file weighs 34692, if you add another 0, then everything, immediately an error.

Answer 1

I found information, it turns out to be the libssh2 library limit on the size of the package, which cannot be changed in any way.