Chat log problems

DataMind Oda keeps each chat's lasting record as a log file on your computer. When it cannot open or save one of those files, it shows a message like the ones on this page. Find your message, read what it means, and follow what to do. Where the files live is on Chat logs on disk; a chat written by another version of Oda is a different case, covered on Opening older chats.

Note

When a log fails one of these checks, Oda refuses to work from it rather than guess, and it leaves the file as it is. Do not edit a log by hand; a hand edit can leave a chat that will not open.

Find your message

Note the message exactly as shown, including the id, line, byte or path in it.
Find it in the tables below and follow the matching row.
Keep any file the message names as it is. If the message returns every time, contact your DataMind OS administrator with it.

A chat that is missing, already saved or in use

Message	What it means	What to do
`session "<id>" not found`	Oda looked for this chat's file and did not find it. The file may have been moved or removed outside Oda.	Check that you are on the computer where the chat was saved. If the file or its folder was moved, put it back, then open the chat again.
`session "<id>" already exists`	A file for this chat is already saved, and Oda will not create another one over it.	Open the chat that is already there. Nothing on disk was replaced.
`session "<id>" is already owned by an active write handle`	Another task or window of DataMind Oda is saving to this chat.	Wait for that task to finish, or close the other window, then try again. Reading the chat is not blocked.
`session "<id>": <operation> is not available on a read handle`	Oda tried to save through a connection that can only read the chat.	Open the chat again and repeat the action. If the message returns, contact your DataMind OS administrator.
`session "<id>": <operation> on a closed handle`	The chat was closed before the action finished.	Open the chat again and repeat the action.

A damaged log file

These messages mean Oda stopped reading a log because part of it is not valid. If you have a backup or a copy of the chat, restore it in place of the damaged file; never edit a log by hand. If you do not, keep the file and the message for your DataMind OS administrator.

Message	What it means	What to do
`session "<id>": stored log is corrupt: <detail> (raw log: <path>)`	The saved file is damaged. The detail repeats the exact check that failed, one of the messages below; the path names the file on your computer.	Keep the file as it is and contact your DataMind OS administrator with this message.
`corrupt session log: header line is not valid JSON`	The first line of the file, which names the chat, cannot be read.	Keep the file as it is and contact your DataMind OS administrator with this message.
`corrupt session log: first line is not a JSON object`	The first line can be read, but it is not a chat header record.	Keep the file as it is and contact your DataMind OS administrator with this message.
`corrupt session log: first line is not a session header`	The first line is not a record Oda recognises as the start of a chat.	Keep the file as it is and contact your DataMind OS administrator with this message.
`corrupt session log: unparsable committed event at line <n>`	A saved part of the file at that line cannot be read.	Keep the file as it is and contact your DataMind OS administrator with this message.
`corrupt session log: invalid committed event at line <n>: <detail>`	The saved part at that line is not valid; the detail says why.	Keep the file as it is and contact your DataMind OS administrator with this message.
`empty or header-less session log`	The file is empty or does not begin with a chat header.	Keep the file as it is and contact your DataMind OS administrator with this message.

A damaged compressed log file

By default, Oda saves chat logs in a compressed form called Zstandard. These messages mean the compressed file is damaged.

Message	What it means	What to do
`corrupt Zstandard session log: invalid frame magic at byte <n>`	The compressed file stops looking like valid compressed data at that byte.	Keep the file as it is and contact your DataMind OS administrator with this message.
`corrupt Zstandard session log: reserved frame-header bit at byte <n>`	A structure check inside the compressed file failed at that byte.	Keep the file as it is and contact your DataMind OS administrator with this message.
`corrupt Zstandard session log: reserved block type at byte <n>`	The compressed file uses a reserved block type at that byte.	Keep the file as it is and contact your DataMind OS administrator with this message.
`corrupt Zstandard session log: first frame is not exactly one header line`	The compressed file must begin with one part holding exactly the chat header, and it does not.	Keep the file as it is and contact your DataMind OS administrator with this message.
`corrupt Zstandard session log: header frame failed validation: <detail>`	The header inside the compressed file failed its check; the detail says why.	Keep the file as it is and contact your DataMind OS administrator with this message.
`corrupt Zstandard session log: complete frame contains a torn JSONL record`	A finished part of the compressed file ends in the middle of a saved record.	Keep the file as it is and contact your DataMind OS administrator with this message.
`empty or header-less Zstandard session log`	The compressed file is empty or has no header.	Keep the file as it is and contact your DataMind OS administrator with this message.

Not every unfinished end is damage. If Oda stops in the middle of a save, the last part of the log can be incomplete; reopening the chat keeps every complete record, and the next write repairs the file. That case is covered on Chat recovery after a crash.

A file that does not match the chat

Message	What it means	What to do
`stored session identity mismatch: requested "<id>", header contains "<meta>"`	The stored file belongs to a different chat than the one being opened.	Keep the file as it is and contact your DataMind OS administrator with this message.
`requested id "<x>" does not match header id "<y>"`	The place Oda opened says one chat, and the file inside says another.	Keep the file as it is and contact your DataMind OS administrator with this message.
`header id "<x>" and cwd identify "<path>"`	The chat id and the working folder saved inside the file point to a different location than the one Oda opened.	Keep the file as it is and contact your DataMind OS administrator with this message.

A file in the wrong form or place

Message	What it means	What to do
`session artifact "<path>" uses <other suffix>, but this backend is configured for compression "<mode>"; use a separate root or select the matching compression mode`	The file is saved in a different form, compressed or plain, than the folder it is in expects.	Keep logs of the two forms in different folders, or open this chat in the copy of Oda that saved it.
`session artifact "<path>" uses the unsupported flat-file layout; use a separate root or move it into a project/session directory before loading`	The file sits directly in the folder that groups chats, not inside a chat folder of its own.	Oda does not load it from there. Move it into the chat folder it belongs to, or keep it in a folder of its own.
`duplicate JSONL session id "<id>" appears in multiple project directories`	The same chat appears in more than one place under the folder where Oda keeps chats.	Oda does not choose between the copies. Keep the one you need and remove the other with care.

When a save is refused

Message	What it means	What to do
`append seq mismatch for "<id>": expected <n> at index <i>, got <m>`	A new part of the chat did not continue the file exactly where it ended, so Oda refused it instead of guessing.	Try the action again. If the message returns, contact your DataMind OS administrator with it.
`session event batch is not losslessly JSON-serializable because it contains non-JSON-serializable data`	A record could not be saved exactly as it was, so Oda refused rather than save a changed version.	Try the action again. If the message returns, contact your DataMind OS administrator with it.

Saved readings rebuild themselves

Oda keeps small summaries of a chat's state so it does not have to read the whole log to show the chat. When a saved reading no longer fits the log, for example after a repair, Oda builds it again from the start of the log instead of serving a value that may be wrong. Nothing is lost, and you do not need to do anything. The rules for these readings are on Chat log format.

Questions, answered

Why does Oda refuse a file instead of repairing it?

Reading a file it does not fully understand could show the wrong history, so Oda refuses rather than guess. A refusal changes nothing: the file stays as it is, and the same message appears if you try again.

Another task is writing my chat. What should I do?

Close the other window or wait for that task to finish, then try again. Reading the chat is not blocked while another task writes to it.

What does the detail in a `stored log is corrupt` message say?

It repeats the exact check that failed, one of the messages listed above, and the bracketed path names the file on your computer. Keep the file and the message for your DataMind OS administrator.

I have a backup of a damaged chat log. How do I use it?

Restore the copy in place of the damaged file, keeping the log's folder and its form: a compressed log stays compressed and a plain one stays plain. Then open the chat again. Do not edit the damaged file by hand; Oda refuses a log that changed outside it rather than guess.

The message says to use a separate root. What does that mean?

A folder of logs is read in one form, either compressed or plain, and this file is in the other form. Keep files of the two forms in different folders, or open the chat in the copy of Oda that saved it.

What does `unsupported flat-file layout` mean?

Each chat lives in a folder of its own, inside a folder that groups chats by the working folder. A log sitting directly in the group folder is not loaded; move it into the chat folder it belongs to. The layout is shown on Chat logs on disk.

The message says the same chat appears in more than one folder. Which copy do I keep?

Oda does not choose between the copies. Keep the one you need and remove the other with care, so the chat has a single saved log again.

What does `is not losslessly JSON-serializable` mean?

A value in that part of the chat could not be stored exactly as it was, so Oda refused rather than store a changed version. Try the action again; if the message returns, keep it for your DataMind OS administrator.

Where do I look when my message is not on this page?

This page covers messages about chat log files. Opening older chats covers files written by another version of Oda, and Chat recovery after a crash covers what happens after a sudden stop. For everything else, see Updates and troubleshooting.