Without exact system info, details about your project and things liek exact render settings nobody can tell you much.
I think it's worth noting that it's been working fine with the same file this morning before I updated, and doesn't anymore since the update to CC 2018
Windows 10 Home 64bit, usually automatically up-to-date via Windows Update, no Fall Creators Update yet.
Intel Core i5-2400 @ 3.1 GHz
Radeon HD 7800 Series graphics card
Render settings (unchanged from what I had used with CC 2017):
PNG (biggest filesize)
Custom document size (372 x 492px)
direct alpha channel
Please let me know if I missed anything important.
Thanks for reporting this miascugh, Could you please PM me the PSErrorlog.txt file?
It seems that there is a missing component in the installation, Request you to reinstall Photoshop CC once and let us know if that helps.
Re-installing Photoshop unfortunately didn't help
Could you please create a new administrative account to test and reproduce this issue?
Refer Adobe troubleshooting: Creating an admin account in Windows
Let us know if the issue persists on the new account.
Hey, very sorry it took so long to get back to you. I finally got around to testing the suggested method as I'll be needing frame rendering to work soon.
Unfortunately I get exactly the same error message with a newly created admin account.
turns out, rendering an image sequence works fine with any format other than *.png - in the worst case I could ask my client if any of the available formats are viable for them, but I'd really rather be able to use *.png-files
Update July 23, 2018: Just tried it again today, and some update along the line seems to have fixed it.