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Error running study online: "when setting the image of ImageSim...? symbols"

Title of task: Social Media Task
Owner: Daniel Shaw (

Description of the problem: We have successfully loaded this task from PsychoPy Builder to Pavlovia (sync success) and Gitlab. When we run the study, it loads appropriately and indicates that it’s downloaded everything, but we then get the following error message:

“Unfortunately we encountered the following error: When setting the image of ImageStim: image the argument…” (see attached)

Any help would be greatly appreciated - this is our first time trialling an online experiment.

Charlotte & Dan

Does it work offline? That error looks like you have an embedded image in your Excel file rather than a file name.

Thanks for your response. It runs fine offline through the Builder, and we don’t have any images in the xls. file; only the stimulus names. We are using tiff image files so not sure if that’s a problem; the end of the error message states “is not an image”.

Tiff images don’t work on web pages. You can batch convert with IrfanView to jpg or png.

Thank you so much; it works!

For anyone else experiencing this problem: TIFF images work in the PsychoPy Builder offline, but do not run online. We had to convert our images to PNG; we used GIMP image manipulator to do this by using the ‘export’ button, but importantly had to ensure that only the following settings were ticked:


Here is a thread that helped us, too: IOError: Found file but it failed to load as an image

Please could you mark your post as the solution?