Exception when calling fetchmessages.php from live help embedding

[marijngiesen]

Describe the bug
When calling fetchmessages.php (the livechat embed calls this), the application throws an 503 error. This only happens when there is some traffic and the page with the livechat embedding has been idle for a while (about 20/30 mins). Out livechat embed first shows a form the user must fill. After submitting the form, the livechat embed shows an empty page and is unresponsive. The logs show the following exception:

[15-Dec-2025 08:28:29 Europe/Amsterdam] PDOException: There is no active transaction in /code/ezcomponents/Database/src/handler.php:222
Stack trace:
#0 /code/ezcomponents/Database/src/handler.php(222): PDO->rollBack()
#1 /code/cache/compiledtemplates/2f87123ff498d5b69abd5362d9e12967.php(2): ezcDbHandler->rollback()
#2 /code/lib/core/lhcore/lhmodule.php(116): include('/code/cache/com...')
#3 /code/lib/core/lhcore/lhmodule.php(678): erLhcoreClassModule::runModule()
#4 /code/index.php(48): erLhcoreClassModule::moduleInit()
#5 {main}

This exception isn't even logged in the application, only in the php error log. This is because the exception is caused by $db->commit on line 274 in /modules/lhwidgetrestapi/fetchmessages.php and caught on line 276, which tries a $db->rollback on line 277. That fails, because there is no transaction and the error write action on line 280 isn't called.

Have you tried to reproduce on official demo? We can't help if we can't reproduce...
No, can't generate enough traffic there.

Have you tried to debug and get debug information?
https://doc.livehelperchat.com/docs/debug

To Reproduce
Steps to reproduce the behavior:

1. Add a live help widget to a page with following settings:

• enable fresh start
• enable show leave message form
• set widget mode to embed

2. Embed the generated code on a page

3. Enable a start chat form with a number of required questions

4. Generate some traffic to the chat server (multiple operators logged in, multiple visitors, etc)

5. Now open the page with the embedded live help. The form will show on the embedded chat.

6. Wait about 20 mins, while traffic is still happening

7. Submit the embedded form. The embedded chat will show nothing but a text box where you can't interact with. The error log will show the "No active transactions" error.

Expected behavior
Chats should work after submitting the form, even if the page has been idle for 20 mins. The exception "No active transactions" should not be thrown.

Screenshots
If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):

• OS: [e.g. iOS] MacOS, ChromeOS, Windows
• Browser [e.g. chrome, safari]: Chrome, Firefox
• Version [e.g. 22]

Additional context
Add any other context about the problem here.

[remdex]

That does not make any sense and I can't reproduce. Waiting 20 minutes should not have nothing to do with transaction. and transaction is always started here
https://github.com/LiveHelperChat/livehelperchat/blob/master/lhc_web/modules/lhwidgetrestapi/fetchmessages.php#L12

The only idea is your server is having in general problem with number of SQL connections and first query fails or in the middle of request your sql connection is lost.

So you will have to look problem on your end or record how you reproduce on official demo.

[remdex]

Just for clarification added more resilient code to record error you are having.

You should see exact error in cache/default.log also in database. But if error is $db->commit() you will have to look for problem yourself as this should never happen unless some your extensions starts and does not commit transaction.

[marijngiesen]

Our MariaDB server is fine (see below). I'm not sure what is causing this. We don't have any extensions installed.

-------- Performance Metrics -----------------------------------------------------------------------
ℹ  Up for: 4d 23h 14m 57s (12M q [29.221 qps], 617K conn, TX: 18G, RX: 6G)
ℹ  Reads / Writes: 98% / 2%
ℹ  Binary logging is disabled
ℹ  Physical Memory     : 15.4G
ℹ  Max MySQL memory    : 861.2M
ℹ  Other process memory: 0B
ℹ  Total buffers: 417.0M global + 2.9M per thread (151 max threads)
ℹ  Performance_schema Max memory usage: 0B
ℹ  Galera GCache Max memory usage: 0B
✔  Maximum reached memory usage: 440.5M (2.80% of installed RAM)
✔  Maximum possible memory usage: 861.2M (5.47% of installed RAM)
✔  Overall possible memory usage with other process is compatible with memory available
✔  Slow queries: 0% (0/12M)
✔  Highest usage of available connections: 5% (8/151)
✔  Aborted connections: 0.00% (5/617416)
✔  Query cache is disabled by default due to mutex contention on multiprocessor machines.
✔  Sorts requiring temporary tables: 0% (0 temp sorts / 2M sorts)
✔  No joins without indexes
✘  Temporary tables created on disk: 30% (571K on disk / 1M total)
✔  Thread cache hit rate: 99% (13 created / 617K connections)
✔  Table cache hit rate: 99% (12M hits / 12M requests)
✘  table_definition_cache (400) is less than number of tables (454)
✔  Open file limit used: 0% (30/32K)
✔  Table locks acquired immediately: 100% (1K immediate / 1K locks)

When looking further, I also see this error:

{
    "error": "SQLSTATE[HY000]: General error: 1020 Record has changed since last read in table 'lh_userdep'",
    "line": 375,
    "file": "\/code\/lib\/core\/lhdepartament\/lhuserdep.php",
    "trace": "#0 \/code\/lib\/core\/lhdepartament\/lhuserdep.php(375): PDOStatement->execute()\n#1 \/code\/lib\/core\/lhuser\/lhuser.php(363): erLhcoreClassUserDep::updateLastActivityByUser(84, 1765896903, 1765896901)\n#2 \/code\/cache\/compiledtemplates\/796731c98c736092a7f4fc8d2ee2b83b.php(2): erLhcoreClassUser->updateLastVisit(0)\n#3 \/code\/lib\/core\/lhcore\/lhmodule.php(116): include('\/code\/cache\/com...')\n#4 \/code\/lib\/core\/lhcore\/lhmodule.php(678): erLhcoreClassModule::runModule()\n#5 \/code\/index.php(48): erLhcoreClassModule::moduleInit()\n#6 {main}"
}

[remdex]

And if that's an error which couses issues. Seems your db server is not handling transactions correctly. As you have module compile enabled i don't know exact row which couses it. As this error i can try to handle.

Just also try to update from master branch you should see error in cache/default.log