Hello @luiwallentin,
I hope things are going well for you.
I’ve reviewed both page URLs. The form does not appear on those pages for me because the login wall is behind.
However, I’ve downloaded the form export file, imported it into the lab site, and tried submitting it in Forminator from the old version to the latest. I couldn’t replicate the issue. This is the submission image for reference: https://monosnap.ai/file/7kAFtvcGTlRL2ZG5VEkvWrDaz9352o.
Could it be an issue with PDF files not uploading successfully? Can you try uploading a small file on the test form and check how it goes?
Lastly, I suggest enabling the “Load From Ajax” option from Form > Edit > Behavior > Rendering > “Load from Ajax” > Enable, which helps load the form using Ajax and resolves most common issues. Also, the upload fields use the same behaviour to upload files.
Please give it a try and share the outcome with us. If the above suggestion doesn’t help, remove the login wall from the test form page so we can take a closer look at the console logs. Currently, there are no errors.
We look forward to hearing from you soon.
–
Kind Regards,
Imran Khan
Hi thanks for the quick reply, and sorry for my long reply time.
I have now updated the form to version 1.50.3, and disabled “logged in submission only”.
I tried with a 50KB PDF, and enabled “Load from Ajax”, but I still get the same error. For testing purposes I have deleted 2 hidden fields which pulled User display name and email.
Here’s the real form: https://www.grafiatryk.com/jf/
Thanks in advance
Hi @luiwallentin ,
I hope you’re doing well.
To test it further, could you please duplicate the form and add it to a test page on your site? We’ll make some test submissions to confirm the error and try to see what is happening there.
I hope to hear back from you soon.
Best Regards,
Williams Valerio
Hi again
Thanks for the reply
I have made a test version, with no email notifications of any kind. Though still with the same error ;-).
https://www.grafiatryk.com/john-frandsen-bestilling-test/
Hi @luiwallentin,
I was able to replicate the issue on my end. While checking the browser console, I noticed a 500 error coming from the admin-ajax.php file, which appears to be related to the problem.
https://ibb.co/S7P1MbBR
A 500 error on admin-ajax.php in WordPress means the server failed while processing an AJAX request. Since admin-ajax.php handles background requests, the root cause is usually server-side.
However, can you please enable WP_DEBUG_LOG and see if any PHP Fatal error is logged while submitting the form?
I hope the following guide comes in handy: https://developer.ww.wp.xz.cn/advanced-administration/debug/debug-wordpress/
Can you please navigate to Tools >> Site Health >> Info and copy the site info to the clipboard and share it with us using Google Drive or Pastebin.com?
Looking forward to hearing back from you and helping you resolve the issue as soon as possible.
Best Regards,
Nebu John
Hi again
I have done as you requested. You can find the results here: https://drive.google.com/drive/folders/1YkqLk4tQV8_rexfNpDF5fZwnfptB4lkV?usp=drive_link
The file “WP Debug on form submit” is what was shown when I submitted the form in the top of page … What I would call the header.
As always I hope this helps with the mystery
Hi @luiwallentin,
I’m afraid, the URL share to the Google Drive is private. Could you please make it public, so that we could view it?
Also, could you please confirm after enabling debug mode, you tried to replicate the issue in form? The related errors will only get added to debug mode when its replaced, so hence double checking.
If not, would also recommend re-trying once to ensure all the related errors are picked in the debug log.
Looking forward to your response.
Regards,
Nithin
Hi again
Sorry – I don’t use Google Drive much, so I forgot that little feature. Here’s the public link:
https://drive.google.com/drive/folders/1YkqLk4tQV8_rexfNpDF5fZwnfptB4lkV?usp=sharing
And yes – I cleared all previous data from the log, and turned on debug so it would only contain the errors regarding to the form submission.
Hope this helps
Hi @luiwallentin
Thank you, I see this fatal error:
“[19-Feb-2026 16:39:55 UTC] PHP Fatal error: Uncaught TypeError: stripos(): Argument #1 ($haystack) must be of type string, array given in /wp-content/plugins/forminator/library/abstracts/abstract-class-field.php:1345
Stack trace:”
I exported once again the form to my lab site and could replicate the issue.
We escalated this problem to our second line support team.
Once finding more information we will let you know. Note, the response time depends on the issue complexity, it is expected to have some delay here.
Best Regards
Patrick Freitas
Super in regards to the fatal error find.
Can I roll the plugin back to v. 1.49 in order for my site/form to function, or do you still need access to the test form on grafiatryk.com with the current version 1.50.3?
Hello @luiwallentin
We are still investigating but you can try to downgrade the plugin version to see if that helps. in our tests in works with version 1.49.2 so you can install that and disable the update for now.
We will get back to you once we find a better solution.
Kind Regards
Amin
Hi @luiwallentin,
We have identified a bug regarding this which is causing the issue and our Forminator team is working on a fix.
The issue is primarily due to the following conditions all using the the upload field with the contains rule in the Submit button:
https://i.imgur.com/5gFvnMK.png
For now untill the bug is fixed, you’ll have to remove the conditions added for the submit button for the Upload field and that should help with resolving the fatal error.
We would also recommend adding this snippet to allow correct file types for upload:
<?php
add_action( 'forminator_before_form_render', 'wpmudev_upload_field_form_check', 10, 1 );
function wpmudev_upload_field_form_check( $id ) {
if ( 2960 === intval( $id ) ) { // Please change 2960 to your form's ID.
add_filter( 'forminator_field_file_markup', 'wpmudev_disallow_other_extensions', 10, 2 );
}
}
function wpmudev_disallow_other_extensions( $html, $field ) {
if ( false === strpos( $field['element_id'], 'upload-' ) ) {
return $html;
}
$html = str_replace( array( '.avif,.heif,.heics,.heifs,', 'avif|heif|heics|heifs|' ), '', $html );
return $html;
}
In the above snippet you’ll need to update the number 2960 with your form ID. You can implement the above code using mu-plugins. Please check this link on how to implement the above code as a mu-plugins:
https://wpmudev.com/docs/using-wordpress/installing-wordpress-plugins/#installing-mu-plugins
Regards,
Nithin
Sorry for the late reply. I only got the time to test the solution now. And it works like a charm. So thank you for the help.
Should I just mark this as solved, or should I leave the ticket open for further testing.
Kind regards Lui
Hello @luiwallentin,
You’re welcome!
We’re glad to hear that our suggestions helped as a workaround. Please feel free to mark this thread as resolved for now.
We have reported the issue to the developers, and they’re working on a permanent fix in future Forminator versions.
Best Regards,
Dmytro
Thank you … marked resolved
