I can help you perform some troubleshooting steps to isolate the issue.
Errors occur when you have overloaded data in your browser. To isolate if this is a browser issue, you'll need to create your transactions using a private browser. This way, if you're able to create your transactions, you can offload some data from your default browser.
Offloading some data allows your browser to process and perform faster. This can also allow you to have a better browsing experience.
You may use these keyboard shortcuts in opening a private browser:
But if you're still unable to add your transactions, you can use another browser.
Please let me know if you have any other questions. I'll be around to help.