Log to File

Log to File

Type: log-to-file  ·  Package: Core Activities v1.0.8

Appends a log line to a text file you choose, in the format [date] [LEVEL] message. Useful when you need to keep a record in a file of your own (an audit trail, a log another system watches, a cumulative report) in addition to the execution log the platform captures.

It is different from Log: log writes to the execution log (the one you see in the debug panel and in the Zoan Cloud logs); log-to-file writes to a file on disk. Use each depending on where you want the message to end up; you can use both at once.

How it works

When the execution reaches the activity, it evaluates the message, formats it as a line ([2026-06-16 10:30:00] [INFO] message) and appends it to the file set in path, creating the file (and its folders) if they don’t exist. Each call adds a new line; it never overwrites what was already there. It does not stop the flow: it records and continues.

• The date uses the machine’s local time, in yyyy-MM-dd HH:mm:ss format.
• The level is written in uppercase ([INFO], [WARNING], [ERROR], [DEBUG]).
• The file is written in UTF-8; each line ends with the system’s line break.
• A relative path, or just the file name (process.log), is resolved against the robot’s working folder, not the project’s: use a full path so you always know where the file ends up. Since version 1.0.8; before, a bare file name made the activity fail.

Required parameters

Parameter	Type	Default	Description
path	string	—	Path of the log file. It is created, along with its folders, if it doesn’t exist. With just the file name, it is written to the robot’s working folder.
message	string	—	The text to log. It can be fixed text in quotes or an expression. If it evaluates to empty, the line has no message.

Optional parameters

Parameter	Type	Default	Description
level	string	"info"	Importance of the message. Values: info, warning, error, debug. Picked from a list (it is not an expression).
timestamp	bool	true	Prefix each line with the date and time. With false the line is [INFO] message.

Output

This activity does not return a value. The result is the line appended to the file.

Example

Keep a log of your own for the invoicing process:

Log to File   path = "C:/logs/invoicing.log"   level = info
              message = "Process started — " + str(rowCount(invoices)) + " invoices"

For Each   items = invoices   itemVariable = invoice
 └─ activities:
      Log to File   path = "C:/logs/invoicing.log"   level = error
                    message = "Invoice " + str(invoice["Number"]) + " has no email"

It produces a file like:

[2026-06-16 09:00:01] [INFO] Process started — 15 invoices
[2026-06-16 09:00:04] [ERROR] Invoice INV-021 has no email

log or log-to-file?

• log → to diagnose the execution; it shows in the Designer panel and in the Zoan Cloud logs. This is usually what you want.
• log-to-file → when you need a persistent file (audit, integration with another system, a log that outlives the platform).

The file does not mask credentials

Unlike Log, what you write here reaches the file as is: if the message contains the value of a credential, it is stored in plain text on disk. Never log credentials, and write to a path the bot has permission for.

Common errors

Message	Cause and fix
'path' is required.	path is empty or its expression returned null.
File or folder access error	The robot’s user has no write permission on that path, or another program has the file locked. Use a folder the robot can write to; to tolerate brief locks, wrap it in a Retry.

Related activities

• Log — write to the execution log (not to a file).
• Append to File — append raw text to a file (without log formatting).
• Try / Catch — write the error caught in the catch to a file.